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MANUAL 


OF 


Veterinary  Microbiology. 


BY 

Professoes  MOSSELMAN  and  LIENAUX, 

National  Veterinary  College,  Gureghem,  Belgium. 


TRANSLATED     AXD     EDITED     BY 

K.  R.  DIXWIDDIE, 

Professor  of  Veterinary  Science,  College  of  Agriculture,  Arkansas  State 

University;  Animal  Pathologist,  Arkansas  Agricultural 

Experiment  Station. 


New  York  : 
WILLIAM   R.  JENKINS, 
851  &  853  Sixth  Avencte  (Cor.  48th  Street). 

1895. 


Ay 

4< 


copybight,  1894, 
^  Bt  R.  E.  DINWIDDIE. 


73^70 


.p 


PREFACE. 


In  undertaking  the  translation  of  MM.  Mosselman 
and  Lienaux's  ^'3fanuel  de  31icrobiologie  Veterinaire" 
my  object  has  been  to  supply  English  speaking  veteri- 
nary students  and  practitioners  with  a  work  on  Bac- 
teriology which   seemed   specially  adapted   to   their 
needs.     The  book  is  small,  but  it  conveys  more  in- 
formation on  the  etiology  of  the  infectious  diseases 
of  animals  and  the  biology  of  the  germs  associated 
with  them  than  any  other  single  work  in  our  lan- 
•  guage.     Unlike  other  works  on  Bacteriology  accessi- 
ble to  readers  of  English  only,  the  Microbiology  of 
animal  diseases  is  treated  of  as  the  essential  part  of 
the  work,  that  of  diseases  of  mankind  only  incident- 
ally referred  to.     The  completeness  and  accuracy  as 
to  details  with  which  it  discusses  the  modes  of  prop- 
agation of  some  of  our  most  important  diseases  and 
the  general  conditions   under  which  these   diseases 
occur,  ought  to   recommend  the  book    to  practical 
veterinarians,  who  are  presumably  more  interested  in 
the  ascertained  facts  in  regard  to  any  disease  than  in 
the  individuality  of  the  germ  which  occasions  it. 

The  book  is  not  intended  for  a  laboratory  manual, 
consequentl}',  the  technique  of  staining  and  cultiva- 

(iii) 


iv  Preface. 

tion  of  germs  is  not  exhaustively  discussed,  and  the 
usual  illustrations  of  bacteriological  apparatus  have 
been  omitted. 

As  to  the  translation  itself  a  few  words  are  neces- 
sary :  Weights  and  measures,  given  in  the  metrical 
system  in  the  original,  have  not  been  changed.  Di- 
mensions which  occur  in  this  work  are  chiefly  those 
of  microscopic  objects  which  are  now  rarely  ex- 
pressed by  American  microscopists  in  fractions  of  an 
inch.  The  thermometric  readings  are  in  all  cases 
given  in  the  centigrade  scale.  For  those  who  are 
unfamiliar  with  the  decimal  system  the  Appendix 
will  supply  the  requisite  information. 

The  few  foot-notes  which  I  have  introduced  are  in 
some  cases  intended  to  be  supplementary  to  the  text, 
referring  to  discoveries  which  have  been  made  since 
the  publication  of  the  original  in  1891.  In  other 
cases  they  are  explanatory  of  words  or  statements 
which  might  otherwise  be  misunderstood. 

To  the  illustrations  which  occur  in  the  French 
text  I  have  added  a  few  others  borrowed  from  difler- 
ent  sources,  which  are  acknowledged  in  the  descrip- 
tions accompanying  the  figures;  four  are  from  draw- 
ings of  preparations  in  my  own  possession. 

R.    R.    DiNWIDDIE. 

Fayetteville,  Ark.,  July  10,  1894. 


i^  a"NIVERSITY 


TABLE  OF  CONTENTS. 


PART  FIRST. 

Generalities  upon  Microbes. 

I. — Microbes  in  the  Static  Condition. 

Definition i\ 

Forms 11 

Organization  and  chemical  composition 14 

Occurrence  and  distribution  in  nature 14 

II. — Physiology  of  Microbes. 

Foods  of  microbes 19 

Digestion  of  microbes 19 

Eespiration  of  microbes 21 

Nutrition  of  microbes 22 

Movements  of  microbes 24 

Generation,  multiplication 25 

Action  of  the  media  on  microbes 27 

Action  of  microbes  on  the  media 30 

Role  of  bacteria  in  nature 30 

Fermentations 81 

Putrefaction 32 

Role  of  bacteria  in  the  normal  organism 33 

Digestive  action  of  microbes 33 

Putrefaction  of  cadavers 34 

E61e  of  microbes  in  tlie  organism  in  the  pathological  con- 
dition   36 

Classification 37 

PART  SECOND. 

Generalities  upon  Pathogenic  Microbes. 

I. — Pathogenic  Microbes  in  the  Static  Condition. 

Saprogenic  or  saprophytic  germs 39 

(V) 


vi  Contents. 

Pathogenic  germs 40 

Conditions  of  existence  of  pathogenic  germs  in  external 

media  and  in  the  economy.     Sources  of  infection 40 

Contagious  obligatory  parasitic  microbes 40 

Contagious  facultative  microbes 41 

Non-contagious  facultative  microbes 42 

Distribution  of  pathogenic  germs 43 

Modes  of  contagion 52 

Immediate  contagion 52 

Direct  contact 53 

Heredity 53 

Mediate  contagion 54 

Absorption  of  pathogenic  microbes 55 

II. — Physiology  of  Pathogenic  Microbes. 

Action  of  microbes  upon  the  organism. '. 61 

Pathogeny  of  the  local  changes 61 

Pathogeny  of  general  and  remote  changes * . . .  63 

Receptivity  65 

Immunity 70 

Reaction  of  the  organism  against  microbes 74 

Phagocytosis 74 

Bactericidal  state 76 

Elimination  of  microbes 78 

Modifications  of  virulence 79 

Evolution  of  the  bacterial  disease 80 

Incubation 81 

Latent  microbism 81 

Specificity  of  pathogenic  microbes 82 

III. — Transformation  and  Destruction  of  Pathogenic  Microbes 

in  their  Relation  to  Hygiene  and  Therapeutics. 

Morphological  and  physiological  variations  of  pathogenic 

microbes ; 85 

Attenuation 87 

Preventive  inoculations ;  vaccinations 94 

Destruction  of  pathogenic  microbes 97 

IV. — Methods  of  Determination  of  Pathogenic  Microbes. 

Basic  and  acid  colors 104 

Examination  of  liquids 106 

Examination  of  organic  pulps 107 

Examination  of  sections 107 


Contents.  vii 

Mounting  of  preparations 108 

Single  stains 109 

Double  stains 110 

Method  of  Loffler 110 

Method  of  Malassez  and  Vignal 110 

Method  of  Gram 110,  111 

Method  of  Weigert Ill 

Method  of  Kiihne 112,  113 

Method  of  Berlioz 114 

Method  of  staining  spores 115 

Culture  of  germs 115 

Sterilization 115 

Culture  media 119 

Isolation  of  bacteria 129 

Inoculation  of  culture  media 130 

Culture  ovens 132 

Experimental  contagions 139 

PART  THIRD. 
Microbic  Diseases  Individually  Considered. 

Microbic  diseases  consecutive  to  wounds 145 

Suppuration 147 

Pysemia 152 

Septicaemia 153 

Pasteur's  sopticsemia 160 

Septicaemias  of  the  rabbit 167 

Koch's  experimental  septicaemia 167 

Spontaneous  septicaemias  of  the  rabbit 168 

Hemorrhagic  septicaemias 323 

Chicken  cholera 170 

Infectious  enteritis  of  chickens 177 

Epizootic  dysentery  of  chickens  and  ducks 177 

Duck  cholera 178 

Bateridian  charbon 180 

Symptomatic  charbon 1 94 

Rouget  of  the  pig 203 

Pneumo-enteritis  or  cholera  of  the  pig 208 

Pneumo-enteritis  of  the  sheep 216 

Infectious,  pneumonia  of  the  pig 218 

Tuberculosis 221 


viii  Contents. 

Tuberculosis,  diagnosis  of  doubtful  cases 233 

Tuberculosis  and  scrofula 246 

Tuberculosis  of  mammals  and  tuberculosis  of  fowls 247 

Tuberculosis,  zoogloeic 251 

Tuberculosis,  bacillar  of  Courmont 253 

Tuberculin 235 

Glanders 254 

Glanders,  diagnosis  of  doubtful  cases 260 

Mallein 260 

Epizootic  lymphangitis 265 

Strangles 265 

Contagious  acne  of  the  horse 267 

Actinomycosis 268 

Botryomycosis 280 

Bovine  farcy 282 

Tetanus 284 

Diphtheria 295 

Eabies 299 

Equine  typhoid  fever .' 311 

Contagious  pneumonias  of  the  horse 313 

Contagious  pleuro-pneumonia  of  cattle 316 

Septic  pleuro-pneumonia  of  calves 320 

Epizootic  abortion 324 

Contagious  mammitis  of  milch  cows 326 

Gangrenous  mammitis  of  milch  ewes 329 

Diseases  of  milk 329 

Bacterial  hsemoglobinuria  of  cattle 332 

Distemper  of  young  dogs 334 

Phosphorescent  meats 338 

Appendix 3"*0 


INTRODUCTION. 


"Works  which  treat  of  Microbiology  are  quite  nu- 
merous, but  none  offer  a  concise  and  complete  expo- 
sition of  the  accepted  facts  on  the  subject,  the  appli- 
cation of  which  is  within  the  reach  of  students  and 
practitioners.  Such  outline  we  would  give  here  in 
the  hope  that  both  may  be  benefited  thereby. 

It  would  seem  that  this  publication  has  some  pros- 
pect of  being  well  received.  Besides  the  fact  that 
the  veterinarian  in  daily  practice  is  under  the  neces- 
sity of  having  recourse  to  the  teachings  of  microbi- 
ology, the  inspection  of  meat  and  the  supervision  of 
the  sanitary  police — duties  which  have  devolved  upon 
him — make  it  his  imperative  duty  to  neglect  no 
means  of  diagnosis  which  science  places  at  his  dis- 
posal. 

"We  do  not  mean  to  assert  that  the  diagnosis  of  in- 
fectious diseases  necessitates  in  all  cases  a  search  for 
the  pathogenic  microbes,  but,  recognizing  the  im- 
portance of  the  pathological  anatomy  and  clinical 
symptoms,  we  believe  that  the  demonstration  of 
these  germs  is  of  much  higher  value.  We  will  even 
say  that,  in  unfortunately  too  many  cases,  the  recog- 

(ix) 


X  Introduction. 

nition  of  the  germs  is  the  only  mode  of  definitely 
establishing  the  nature  of  a  lesion. 

Every  one  can  understand  how  desirable  it  is  that 
the  practitioner,  meat  inspector  or  sanitary  veterina- 
rian, whose  decisions  very  frequently  run  counter  to 
some  particular  interest,  should  pronounce  himself 
only  after  having  made  use  of  this  last  resource 
which  will  protect  him  from  scientific  mistakes  and 
contradictions,  always  much  to  be  regretted. 

A  like  exactitude  is  to  be  desired  in  private  prac- 
tice, where  it  will  form  a  basis  for  sound  therapeutics. 

"We  will  briefly  trace  the  history  of  those  microbes 
which  may  be  of  interest  to  the  practitioner,  and  de- 
scribe the  technique  of  those  investigations  which  he 
may  daily  be  called  upon  to  make.  Our  study  will 
embrace  three  divisions.  In  the  first  we  will  briefly 
consider  the  subject  of  microbes  in  general  ;  in  the 
second  we  will  study  pathogenic  germs  collectively ; 
and  in  the  third  notice  those  particular  microbes 
which  occasion  disease  in  animals  and  even  in  man- 
kind. 


OF  VETERINARY  MICROBIOLOGY. 


PART   FIRST. 
MICROBES  CONSIDERED  IN  GENERAL. 

Microbes   may  be   considered   successively  in   the 
static  and  in  the  functional  or  physiological  condition. 


CHAPTER  I. 

MICROBES    IN   THE    STATIC    CONDITION. 

Definition — 1.  Forms  of  microbes;   2.  Organization  and  chemical 
composition ;    3.  Situation  and  distribution. 

The  names  3Iicrobes,  Bacteria,  Vibrios,  Schizomycetes, 
Schizophijtes,  have  been  given  to  unicellular  micro- 
scopic beings  placed  at  the  bottom  of  the  scale  of 
the  vegetable  kingdom.  These  beings,  destitute  of 
chlorophyll,  live  at  the  expense  of  complex  organic 
substances,  which  they  reduce  to  the  condition  of 
simple  mineral  compounds. 

I.  Forms  of  microbes. 

1.  Typical  forms. — The  form  of  microbes  is  that  of 
a  rounded  corpuscle  or  of  a  rod.  The  latter  may  be 
straight,  undulated,  or  spiral. 


12 


3Ianual  of  Veterinary  Microbiology. 


Fig.  I. 


Rounded  microbes  or  cocci  have  received  the  follow- 
ing names,  according  to  the  manner  in  which  they  are 
grouped: 

3Iicrococcus :  cocci  isolated, 

(Fig.  1, 1) ; 

Diplococcus:  cocci  arranged 
in  pairs,  (2) ; 

Streptococcus :  cocci  ar- 
ranged in  linear  series,  in 
chains,  (3) ; 

Hicrococcus  tetragenus:  cocci 
arranged  in  groups  of  four, 

(^); 

Sarcina :  cocci  arranged  in 
tetrads  so  as  collectively  to 
form  a  cube. 

Staphylococcus :  cocci  associated  in  clusters ; 

Zobgloca:  cocci  associated  in  large  numbers  in  an 
amorphous  matrix,  (5) ; 

Ascococcus :  cocci  associated  in  large  numbers  in  an 
amorphous  matrix  and  inclosed  in  an  enveloping  mem- 
brane, (6). 

The  elongated  microbes  are  cylindrical  or  fusiform 
rods,  or  have  the  shape  of  a  bell  clapper.  They  have 
received  the  following  names  : 

Bacillus :  rods  short  and  straight,  (7) ; 

Leptothrix:  rods  long  and  undulating,  (8) ; 

Cladothrix:  rods  long,  straight,  and  branching,  (9). 

Spiral  microbes  are  in  the  form  of  an  arc  of  a  circle, 
or  are  spiral.  They  appear,  however,  with  rectilineal 
forms  when  their  curvature  is  directed  toward  the  ob- 


jective, 
them : 


The  following:  terms  are  used  to  designate 


Microbes  in  the  Static  Condition.  13 

Vibrio  :  microbes  spiral,  short,  (10) ; 

Spirillum  :  microbes  spiral,  long  and  rigid,  (11) ; 

Spirochete:  microbes  spiral,  long  and  flexible,  (12). 

2.  Forms  of  involution,  of  degeneration. — Under  spe- 
cial conditions  unfavorable  to  their  nutrition  bacteria 
may  assume  abnormal  aspects,  such  as  swelling  in  the 
form  of  a  club,  at  which  place  the  protoplasm  becomes 
clearer  :  these  special  forms  are  called  forms  of  invo- 
lution, (14).  They  have  been  established  in  the  acti- 
nomyces,  the  bacillus  of  Koch,  etc. 

3.  Polymorphism. — Microbes  are  essentially  poly- 
morphic. Recent  researches  have  shown  that  the 
same  microbe  may  assume  very  ditFerent  aspects,  ac- 
cording to  the  medium  in  which  it  lives.  Thus,  the 
germ  of  the  pyocyanic  disease  presents  itself  succes- 
sively as  a  bacillus,  a  spirillum,  and  a  micrococcus. 
The  bacillus  of  Pasteur's  septicemia  grows  in  long 
filaments  in  the  blood,  in  short  bacilli  in  the  subcu- 
taneous cellular  tissue.  The  bacillus  of  symptomatic 
charbon,  cultivated  in  bouillon  containing  glycerin 
and  sulfate  of  iron,  takes  the  form  of  a  clove.  With 
the  same  germ,  therefore,  we  can  obtain  several  mor- 
phologically distinct  individualities. 

The  dimensions  of  microbes  are  as  variable  as  their 
form ;  in  all  cases  these  are  expressed  by  a  few  thou- 
sandths or  even  fractions  of  the  thousandth  of  a  milli- 
meter.* 

*  [The  dimensions  of  microscopic  objects  are  usually  expressed 
in  Microns.  A  micron  is  the  one  thousandth  part  of  a  millimeter, 
and  is  designated  by  the  Greek  letter  jW.  The  dimensions  of 
microbes,  expressed  in  the  original  of  this  work  in  decimal  frac- 
tions of  a  millimeter,  have  been  rendered  in  the  translation  as 
microns.     Thus  0mm.,  005=-5/i. — D.] 


14  Manual  of  Veterinary  Microbiology. 

II.   Organization  of  microbes. 

Structure  and  chemical  composition. — The  structure 
of  microbes  may  be  compared  to  that  of  a  cell  with- 
out nucleus.  The  existence  of  the  latter  is  not  gener- 
ally admitted,  although  some  authorities  believe  they 
have  observed  such  a  structure. 

The  content  is  a  kind  of  protoplasm  which  Nenki 
has  designated  by  the  name  of  mycoprotein,  a  homo- 
geneous, or  sometimes  granular,  substance  generally 
devoid  of  color.  Under  certain  circumstances  it  may 
contain  brilliant  corpuscles  (spores),  starch  grains  (in 
the  Sarcina),  and  granules  of  sulphur  (Beggiotoa). 

The  periphery  is  formed  by  a  thin  and  flexible,  or 
thick  membrane,  the  nature  of  which  is  not  well 
known.  Most  authors  look  upon  it  as  a  carbo-hydrate 
allied  to  cellulose ;  its  resistance  to  acids  and  alkalies 
seems  to  support  this  view.  Others  regard  it  as  a 
layer  of  mycoprotein  difierentiated  from  the  proto- 
plasm. 

Sometimes  this  membrane  emits  vibratile  cilia ;  at 
other  times  it  is  surrounded  by  a  zone  of  a  mucilagi- 
nous aspect,  capable  of  swelling  up  in  water  and  form- 
ing a  transparent  capsule  to  the  germ  (pneumococcus). 

III.  Situation  and  distribution  of  germs  in  nature. 

The  part  which  these  beings  play  in  nature  being 
known,  it  is  easy  to  understand  that  they  should  be 
found  wherever  there  is  organic  matter  to  be  reduced. 
We  find  them,  indeed,  pullulating  in  all  places  where 
there  are  no  special  conditions  prejudicial  to  their  life. 
We  will  notice  their  distribution  in  the  most  impor- 


Microbes  in  the  Static  Condition.  15 

tant  media :  atmospheric  air,  waters,  soil,  foods,  the 
living  organism,  dwellings,  vehicles,  clothing,  etc. 

Air. — The  germs  which  are  found  suspended  in  the 
atmosphere  can  not  multiply  there,  and  hence  come 
from  other  media  from  which  they  are  carried  off  by 
atmospheric  currents  along  with  pulverulent  matters. 
They  are  deposited  in  the  calm  (tranquil  air,  hollow 
places).  Their  number  and  nature  vary  with  climatic 
and  other  conditions  ;  their  number  increases  during 
desiccation  of  the  soil  (summer),  and  diminishes  after 
rains.  They  are  most  'numerous  in  inhabited  places 
and  in  the  vicinity  of  marshes,  whilst  the  air  of  moun- 
tains and  of  the  surface  of  seas  is  almost  completely 
free  from  them. 

The  germs  of  the  air  do  not  long  resist  the  com- 
bined action  of  oxygen  and  light ;  nevertheless,  through 
the  agency  of  the  winds  their  effects  may  be  mani- 
fested at  great  distances. 

The  study  of  atmospheric  germs  is  made  by  simple 
enumeration  with  the  microscope  or  by  various  cul- 
ture processes.  The  latter  method  is  much  to  be  pre- 
ferred since  it  allows  of  the  separation  of  dead  germs, 
the  number  of  which  is  very  large. 

Watei^s. —  Subterranean  waters,  having  filtered 
through  thick  layers  of  earth,  are  free  from  all  germs, 
but  quickly  become  infected  on  contact  with  the  surface 
soil  and  the  air.  The  waters  of  wells  are  always  in- 
fected; their  pollution  is,  moreover,  easy  to  under- 
stand :  the  masonry  having  no  support  at  the  bottom 
eventually  sinks  down  and  fissures  are  produced 
through  which  infiltrate  the  waters  of  the  neighboring 
surface  soils  often  impregnated  with  germs.     For  this 


16  Ilanual  of  Veterinary  Microbiology. 

reason  wells  should  not  be  built  in  proximity  to  cis- 
terns, cess-pools  or  dung-hills. 

The  deep  waters  best  protected  against  infection 
are  those  of  artesian  wells. 

Surface  waters  are  always  very  rich  in  germs,  the 
nature  of  which  is  extremely  variable ;  the  majority 
are  ubiquitous  germs,  pathogenic  being  much  less  fre- 
quent. Stagnant  waters  especially  favor  the  multipli- 
cation of  germs. 

Soil. — Whilst  the  rocks  and  the  virgin  soil  from  the 
depths  are  free  from  all  germs,  these  occur  in  large 
numbers  in  the  superficial  layers.  Their  number  and 
nature  vary  infinitely  according  to  location,  season, 
winds,  the  physical  constitution  and  chemical  com- 
position of  the  soils,  etc.  Their  multiplication  grad- 
ually decreases  as  the  depth  increases.  Water,  in 
filtering  through  the  ground,  yields  up  the  germs 
which  it  contains  as  well  as  the  soluble  matters  which 
serve  for  their  nutrition. 

It  may  be  said,  in  truth,  that  germs  in  way  of  pul- 
lulation,  through  their  power  of  penetrating  the  cap- 
illary spaces,  should  of  themselves  sink  below  the 
layer  of  soil  in  which  the  waters  deposit  them.  This 
vegetation,  however,  is  itself  impeded  by  unfavorable 
conditions  of  temperature  and  nutrition,  the  absence 
of  oxygen,  etc.  Hence  in  good  filtering  soil  germs 
are  no  longer  found  at  a  depth  of  three  meters. 

Foods. — Vegetable  foods  (fodders,  oats,  etc.)  are  al- 
ways contaminated  with  germs  derived  from  the  air, 
the  soil,  or  waters.  Animal  foods  are  generally  con- 
taminated by  contact  with  the  air.  Foods,  whether 
of  vegetable  or  animal  origin,  are  especially  favorable 
to  the  multiplication  of  microbes.     The  various  means 


Microbes  in  the  Static  Condition.  17 

employed  for  the  preservation  of  foods  have  no  other 
ahn  than  to  protect  them  against  the  invasion  or  the 
destructive  action  of  these  organisms.  When  these 
means  are  defective  or  powerless  to  arrest  the  evolu- 
tion of  the  germs  which  have  been  deposited  there, 
various  changes  supervene  which  diminish  the  in- 
trinsic nutritive  value  of  the  foods  and  may  even  ren- 
der them  detrimental  to  the  health  of  man  or  of  ani- 
mals (damaged  hay,  putrid  meat).  The  contamina- 
tion of  foods  by  pathogenic  germs,  properly  so  called, 
will  be  studied  later. 

Houses  and  vehicles. — The  walls,  floor,  and  ceiling,  as 
well  as  the  mangers  and  racks,  of  houses  occupied  by 
animals  are  constantly  liable  to  receive  the  germs 
which  are  borne  in  the  atmospheric  dust,  cleansing 
waters,  solid  dejections,  litter,  foods,  etc. 

Vehicles  (wagons,  etc.)  serving  for  the  transport  of 
animals  may  be  contaminated  by  microbes  in  the  same 
way  as  houses. 

Havjiess,  blankets^  tools,  and  other  objects. — It  is  easy 
to  understand  that  these  objects  will  most  frequently 
be  contaminated  either  by  the  various  methods  men- 
tioned above  or  by  their  contact  with  the  animal  for 
the  use  of  which  they  are  destined. 

Organism. — After  what  we  have  said  of  the  nutrition 
of  germs,  we  may  expect  to  encounter  them  in  all 
parts  of  the  economy  which  are  in  direct  relation 
with  the  air,  or  with  solid  and  liquid  media. 

The  digestive  canal  throughout  all  its  course  con- 
tains in  large  numbers  various  microbic  species  which 
have  been  carried  there  by  food  and  drink.     In  the 
mouth  we  find  especially  a  leptothrix,  spirochsete,  and 
2 


18  Manual  of  Veterinary  Microbiology. 

vibrios;  from  it  have  also  been  isolated  pathogenic 
germs — staphylococcus  pyogenes,  etc. 

The  stomach  contains  especially  sarcinae,  yeasts, 
and  elongated  bacteria,  whilst  the  intestines  contain 
large  numbers  of  bacilli.  Micrococci  and  elongated 
non-sporulated  bacteria  are  killed  by  contact  with  the 
gastric  juice,  and,  consequently,  do  not  multiply  in 
the  intestine. 

The  mucus  of  the  anterior  respiratory  passage  is 
likewise  always  contaminated  with  germs  which  have 
been  deposited  by  the  inspired  air,  the  latter  itself  be- 
ing thus  purified  so  as  to  emerge  free  from  all  germs. 
Hence,  it  apppears  that  disease  infection  can  not  take 
place  through  the  expired  air.  The  ocular  mucosa 
and  genito-urinary  mucosa  near  the  external  openings 
contain  also  a  certain  number  of  microbes. 

Finally,  these  are  found  lodged  upon  the  skin,  the 
perspiration  and  sebaceous  secretion  along  with  the 
epidermic  debris  normally  cast  off  constituting  a  good 
medium  for  their  preservation. 

The  blood  of  healthy  animals  is  free  from  germs. 
In  the  pathological  condition,  on  the  other  hand,  most 
of  the  tissues  and  fluids  of  the  organism  may  become 
the  seat  of  the  evolution  of  bacteria. 


Physiology  of  Microbes.  19 


CHAPTER  11. 

PHYSIOLOGY    OF    MICROBES. 

1.  Digestion.— 2.  Respiration.— 3.  Nutrition.— 4.  Movements.— 
5.  Generation  and  multiplication. — 6.  Action  of  the  media 
upon  microbes.— 7.  Action  of  microbes  upon  the  media. — 
8.  Classification. 

I.  Digestion. 

1.  Foods. — Microbes  being  destitute  of  chlorophyll 
require  for  their  nutrition  organic  products  already 
formed;  consequently  they  must  nourish  themselves 
at  the  expense  of  vegetable  or  animal  substances. 
They  borrow  nitrogen  from  albuminoid  substances  or 
their  derivatives  as  well  as  from  ammoniacal  salts,  and 
occasionally,  in  part,  from  nitrates  ;  carbon  and  hy- 
drogen from  hydrated  carbonaceous  substances — 
sugar,  glycerin,  and  salts  of  malic,  tartaric  and  acetic 
acids. 

They  require  also  mineral  substances — sulfates  and 
phosphates  of  sodium,  potassium,  and  magnesium. 

They  are  very  sensitive  to  the  chemical  composition 
of  the  nutrient  medium  in  which  they  live ;  traces  of 
certain  substances,. as  well  as  the  absence  of  others, 
can  bring  about  profound  alterations  in  the  manifesta- 
tions of  their  vitality. 

Their  medium  should  be  slightly  alkaline  and  very 
aqueous.  Excess  of  acidity  or  of  alkalinity,  acidity 
especially,  is  prejudicial  to  their  growth. 

2.  Digestion. — The  foods  of  microbes,  like  those  of 


20  3Ianual  of  Veterinary  3Ilcrohiology. 

animals  and  vegetables,  independent  of  the  chloro- 
phyllic  function  of  the  latter,  require  to  undergo  cer- 
tain modiiications  preparatory  to  assimilation.  These 
modifications,  representing  the  digestion  of  microbes, 
consist  of  a  hydration  accompanied  or  not  by  a  split- 
ting up  of  molecules. 

This  phenomenon  is  accomplished  by  means  of  sol- 
uble ferments  secreted  by  the  germs,  and  it  is  remark- 
able that  these  digestive  ferments  are  the  same  as 
those  which  are  found  in  higher  beings  ;  thus,  in  the 
case  of  microbes  as  for  these  last,  starch  is  transformed 
into  dextrin  by  a  diastase^  called  amylase  correspond- 
ing to  vegetable  diastase,  ptyalin,  and  to  the  amyla- 
ceous ferment  of  the  pancreatic  juice.  Cane  sugar  is 
split  up  into  glucose  and  levulose  by  a  diastase  or 
sucrase  identical  with  the  invertin  of  the  beet-root 
and  with  the  inverting  ferment  of  the  intestinal  juice  ; 
albuminoid  substances  are  peptonized  by  microbes 
through  the  secretion  by  the  latter  of  a  special  pepsin 
or  casease ;  in  the  case  of  the  casein  of  milk  the  ac- 
tion of  this  last  substance  is  preceded  by  that  of  a  dias- 
tase analogous  to  rennet  which,  like  the  latter,  deter- 
mines the  coao-ulation  of  the  milk. 

When  we  consider  the  great  number  of  germs  con- 
tained within  the  digestive  canal,  the  comparison 
which  we  have  just  made  between  digestion  in  mi- 
crobes and  in  the  higher  beings,  indicates  the  possi- 
bility of  an  adjuvant  action  of  the  former  in  the  di- 
gestion of  animals. 

•(i)The  name  diastase,  formerly  limited  to  the  amylaceous  fer- 
ment of  vegetables,  is  now  synonymous  with  soluble  ferment, 
thus  amylase,  sucrase,  pepsin,  rennet  (presure),  are  diastases  or 
xymases. 


Physiology  of  Microbes.  21 

These  are  not  the  only  diastases  secreted  by  mi- 
crobes. We  are  far  from  knowing  all  of  them ;  they 
vary,  naturally,  according  to  the  special  nature  of 
their  food.  We  have  noted  the  principal  of  them  in 
order  to  bring  out  the  general  mode  of  the  nutritive 
process  in  microbes. 

II.  Bespiration. 

The  study  of  the  respiration  of  microbes  is  of  great 
interest.  Obviously,  all  require  oxygen  which,  in  ox- 
idizing alimentary  substances,  supply  the  heat  neces- 
sary for  the  maintenance  of  life,  for  multiplication 
and  motion,  etc.  Many  of  them  borrow  it  in  the  free 
state  from  the  atmosj)here  or  from  water  {aerobes),  but 
there  are  others  which  appear  incapable  of  enduring 
free  oxygen,  hence  require  to  live  protected  from  the 
air  {anaerobes).  These  last  act  upon  certain  organic 
substances  by  a  sort  of  internal  combustion ;  they  re- 
duce these  substances  into  carbonic  acid  and  into  other 
molecules  generally  less  complex,  but  still  susceptible 
of  oxidation,  setting  free  a  certain  amount  of  energy, 
as  the  aerobic  germs  on  their  part  do  by  a  true  com- 
bustion. 

One  of  the  prominent  characters  of  anaerobic  germs 
when  they  are  nourished  at  the  expense  of  quaternary 
substances  consists  in  the  disengagement  of  abundant 
gaseous  products,  among  which  we  find,  besides 
carbonic  acid,  nitrogen,  ammonia,  and  ammoniacal 
compounds  (trimethylamin,  etc.),  sulfuretted  and 
phosphoretted  hydrogen,  etc.;  these  mixtures  emit  a 
peculiarly  fetid  odor  (putrid  gases).  When  they  es- 
pecially reduce  ternary  products  these  anaerobes  give 
as  gases  carbonic  acid,  hydrogen,  and  hydro-carbons. 


22  Manual  of  Veterinary  3Iicrobiology . 

A  certain  number  of  germs  accommodate  themselves 

equally  well  to  both  these  ways  of  life;   in   the  air 

they  are  aerobic,  in  its  absence  they  become  anaerobic. 

Tliis  double  faculty  has  been  expressed  by  the  term 

a'ero-anaerobic. 

III.  Nutrition. 

1.  Absorption  and  assimilation. — Absorption  of  food 
takes  place  by  osmosis.  A  part  of  the  principles  ab- 
sorbed is  utilized  for  the  elaboration  of  plastic  mate- 
rial ;  another  part  behaves  as  a  respiratory  food.  The 
formation  of  plastic  material  must  be  considerable 
when  we  take  into  account  the  excessively  rapid  mul- 
tiplication of  micro-germs. 

The  respiratory  foods  serve  especially  for  the  pro- 
duction of  the  diilerent  forms  of  work  performed  by 
the  elements,  and  which  are  represented  by  the  phe- 
nomena of  assimilation,  growth,  locomotion,  heat, 
sometimes  light  (phosphorescence  of  meat  and  fish). 

Their  intimate  nutrition  is  little  known.  Chemi- 
cally, the  point  of  departure  of  the  nutritive  action  is 
quite  dift'erent  according  to  the  case.  Some  require 
albuminoids,  whilst  others  draw  their  nitrogen  from 
azotized  products  with  molecules  of  much  less  com- 
plexity: leucin,  tyrosin,  xanthin,  etc.;  others  again 
borrow  it  from  trimethylamin  and  from  ammoniacal 
salts.  The  same  variety  is  observed  in  the  case  of 
non-nitroffenous  foods. 

This  peculiarity  accounts  for  the  successive  appear- 
ance of  different  bacteria  in  an  organic  medium  aban- 
doned to  the  external  air.  As  this  medium  becomes 
more  and  more  exhausted  those  species  of  germs  suc- 
cessively appear  whose  lesser  requirements  permit  of 


Physiology  of  Microbes.  23 

their  living  at  the  e^xpense  of  the  nutritive  residue  of 
those  which  have  preceded  them. 

2.  Disassimilation,  excretions,  secretions. — From  the 
preceding  considerations  it  results  that  disassimilation 
in  microbes  ought  to  give  very  varied  residues.  These 
residues  naturally  depend  upon  the  food,  upon  the 
species  of  germ,  and  upon  the  special  conditions  in 
which  their  evolution  is  accomplished  (temperature, 
aerobic  or  anaerobic  nature,  etc.). 

Of  these  residual  or  excrementitial  products  of  mi- 
crobes some  are  gaseous  (carbonic  acid,  hydrogen,  car- 
buretted  hydrogen,  sulfuretted  hydrogen,  ammonia), 
some  volatile  (trimethylamin,  alcohol,  formic,  acetic, 
butyric  acids,  etc.),  some  fixed  (lactic  and  malic  acids, 
leucin,  taurin,  tyrosin,  etc.,  etc.). 

The  nutrition  of  germs  may  give  rise  to  coloring 
matters,  such  germs  being  called  chromogenic.  The 
coloring  matter  thus  produced  may  be  soluble  or  in- 
soluble ;  in  the  former  case  it  diffuses  in  the  fluid 
media  in  which  the  germs  occur,  an  instance  of  which 
may  be  seen  in  the  germ  of  blue  milk. 

Among  the  number  of  the  substances  resulting 
from  the  nutrition  of  microbes  we  have  to  mention 
the  ptomaines. 

Ptomaines  are  ammoniacal  compounds  acting  the 
part  of  bases,  and  which,  upon  the  higher  beings, 
have  often  effects  analogous  to  those  of  the  vegetable 
alkaloids,  which  they  resemble  in  every  respect. 

In  a  general  way  the  residual  products  are  noxious 
to  the  germs  from  which  they  spring :  0.8  per  cent  of 
free  butyric  acid  arrests  the  butyric  fermentation  of 
lactate  of  lime. 

The  diastases  must  also  be  cited  among  the  products 


OP  THE 

TJ^^TV■E■RRTT^'" 


£-1  Manual  of  Veterinary  Microbiology. 

of  the  nutrition  of  n'licrobes ;  tliev  are  secreted  for 
the  requirements  of  digestion,  as  we  have  already 
seen. 

Later,  we  shall  have  occasion  to  see,  when  consid- 
ering the  role  of  microbes,  that  their  nutrition  is  the 
determining  cause  of  the  chemical  reactions  which 
characterize  fermentations  and  putrefaction. 

rV".  3Iovements  of  microbes. 

Some  bacteria  are  immobile  (the  majority  of  round 
and  some  elongated  bacteria),  others  are  gifted  with 
the  faculty  of  moving  themselves  in  the  jiuids  in 
which  they  live. 

The  kind  of  movement  varies  with  the  species  con- 
cerned ;  sometimes  the  element,  maintaining  its  recti- 
lineal direction,  performs  a  simple,  more  or  less  regular 
oscillation  around  an  imaginary  longitudinal  axis ;  at 
other  times  it  undero-oes  a  slis^ht  inflection  in  the  di- 
rection  of  its  length  and  straightens  itself  again  alter- 
nately ;  at  other  times,  again,  it  assumes  a  flexuous  ap- 
pearance simulating  the  movements  of  a  snake  ;  some 
even  wind  themselves  around  in  corkscrew  fashion. 

The  motion  of  a  certain  number  of  bacteria  is  de- 
pendent upon  the  presence  of  vibratile  prolongations,  in 
others  these  movements  seem  to  depend  upon  contrac- 
tions taking  place  within  the  body  of  the  element. 

In  all  they  are  directly  dependent  upon  nutrition 
the  integrity  of  which  is  necessary  to  their  produc- 
tion. 

Light  and  the  fluidity  of  the  media  are  conditions 
which  favor  them. 


Philosophy  of  Ificrobes.  25 

V.  Generation,  multiplication. 

1.  Spontaneity. — Formerly  it  was  supposed  that  mi- 
crobes originated  by  spontaneous  generation  in  putre- 
factive media;  this  origin,  indeed,  was  accepted  for 
all  beings  the  mode  of  reproduction  of  which  was  un- 
known. The  progress  of  the  natural  sciences  first 
considerably  restricted  the  scope  of  this  theory,  which 
the  experiments  of  Pasteur  triumphantly  and  abso- 
lutely combatted.  Although  it  can  not  be  denied  that 
at  a  period  in  the  remote  past  organized  matter  must 
have  been  formed  spontaneously  at  the  expense  of 
mineral  matters,  it  seems  well  established  now  that 
the  molecular  association  which  tends  to  the  constitu- 
tion of  protoplasm  is  no  more  produced,  at  least 
within  the  conditions  of  observation  accessible  to  man, 
except  at  the  expense  of  a  pre-existent  being.  We 
therefore  have  to  consider  here,  from  a  practical 
point  of  view,  only  the  reproduction  of  germs  by  mul- 
tiplication. 

2.  Fission. — Microbes  multiply  principally  by  fission. 
The  cells  of  which  they  are  composed  become  elon- 
gated, then  divided  into  two  by  a  transverse  groove  ; 
the  two  segments  which  result  from  this  division  may 
separate  and  live  independently  or  may  remain  united 
so  as  to  form  agglomerations  of  various  kinds  ;  for 
example :  the  chains  or  chaplets  of  micrococci 
which  adhere  end  to  end ;  the  zoogloea  to  which  the 
same  micrococci  give  rise  when  united  in  mass  by  a 
gelatinous  substance,  the  jointed  filaments  of  the  an- 
thrax bacillus,  etc. 

Fission  usually  takes  place  in  one  direction  only, 
3 


26  Manual  of  Veterinary  Microbiology. 

but  there  are  bacteria  in  which  the  division  takes 
place  in  two  crossed  directions  (micrococcus  tetra- 
genus),  or  even  in  three  directions  (sarcina) ;  in  this 
last  case  the  bacteria,  the  secondary  elements  of  which 
remain  united,  take  the  form  of  a  cube. 

3.  Sporulation. — Multiplication  by  fission  appears  to 
be  the  only  mode  possessed  by  microbes  of  spherical 
form;  in  the  majority  of  others  we  recognize  a  second 
mode, — sporulation  (13).  This  consists  in  the  forma- 
tion within  the  bacteria  of  brilliant  points  which  are 
apparently  the  result  of  a  condensation  of  the  orig- 
inal protoplasm,  whilst^the  latter  at  the  same  time  be- 
comes very  clear.  These  brilliant  points  are  the 
spores ;  they  are  set  at  liberty  by  the  destruction  of 
the  cell  which  has  produced  them  and  when  they 
find  themselves  in  good  conditions  of  temperature  and 
humidity,  and  in  a  suitable  medium,  they  reproduce 
the  bacteria  as,  in  the  higher  forms  of  vegetation,  the 
seed  gives  origin  to  the  entire  plant. 

Spores  show  a  remarkable  resistance  to  the  action 
of  the  common  causes  of  destruction  of  microbes. 
They  almost  never  develop  in  the  media  in  which  they 
have  taken  birth. 

Botanists  recognize,  besides  fission,  which  for  them 
is  only  a  form  of  growth,  or  vegetation,  two  methods 
of  sporulation  or  fructification.  The  first  and  best' 
known  is  endosporulation  which  we  have  just  described; 
the  second  which  it  is  not  always  easy  to  distinguish 
from  fission  has  received  the  name  arthrosporulation. 
It  is  characterized  by  the  production  by  fission,  at  the 
expense  of  cells  performing  the  function  of  repro- 
ductive elements,  of  new  cells  which  differ  from  those 
obtained  by  ordinary  fission  by  their  state  of  latent 


f 


OF  fr 


Philosophy  of  Blicrobes.  27 

life  and  by  the  thickness  and  resistance  of  their  en- 
veloping membrane.  They  are  generally  larger  than 
the  spores  begotten  by  endosporulation  and  resemble 
cysts.  It  is  this  distinction  in  the  mode  of  formation 
of  spores  which  serves  as  the  fundamental  basis  of 
the  classification  of  Guiguard  which  we  will  reproduce 
later. 

It  is  not  without  interest  to  have  an  idea  of  the 
power  of  multiplication  possessed  by  these  micro- 
organisms. If  we  regard  a  bacterium  as  dividing 
itself  into  two  after  one  hour,  we  will  have  four  of 
them  in  two  hours,  and  in  twenty-four  hours,  16,000,- 
000.  After  forty-eight  hours  we  will  have  the  fabu- 
lous number  of  280  trillions.  We  can  estimate  from 
this  the  ravages  that  germs  introduced  into  the  blood 
must  produce  when  they  find  there  conditions  favor- 
able to  their  pullulation. 

VI.  Action  of  the  media  upon  microbes. 

The  medium  has  necessarily  a  great  influence  upon 
microbes.  Besides  supplying  them  with  food  it  is 
capable  of  modifying  their  vitality  in  different  de- 
grees. 

Certain  agents  or  conditions  have  the  power  of 
bringing  bacteria  to  the  condition  of  latent  life,  of 
changing  their  usual  mode  of  activity,  or  even  of  de- 
stroying them.  These  agents  or  conditions  are  of  a 
nature  either  mechanical,  physical,  chemical,  or  phys- 
iological. 

1.  Mechanical  influences. — These  are  badly  deter- 
mined ;  some  authors  claim  to  have  observed  that 
oscillations  impressed  upon  cultures  of  microbes  are 


28  Manual  of  Veterinary  Microbiology. 

adverse  to  their  multiplication  ;  other  experimenters 
have  arrived  at  directly  opposite  results. 

2.  Physical  influences. — a)  Humidity. — Water  is  in- 
dispensable to  microbes;  a  medium  containing  less 
than  sixty  per  cent  of  this  liquid  arrests-  their  multi- 
plication. Desiccation  causes  all  active  life  to  cease 
(latent  life)  and  may  in  this  way  finally  lead  to  their 
death. 

Similarly,  it  is  to  their  deficiency  in  water  content 
that  we  must  attribute  the  preservation  of  vegetable 
juices  by  sugar,  of  meat  pastry  by  fat,  etc. 

b)  Temjperature. — A  temperature  too  high  or  too 
low  is  detrimental  to  microbes.  They  are  generally 
more  sensitive  to  an  elevation  of  temperature  than  to 
a  depression.  The  vegetative  forms  are  killed  by  two 
hours'  exposure,  to  a  temperature  of  48°  to  60°  C.  The 
spores,  however,  are  much  more  resistant  and  require 
for  their  destruction  a  temperature  of  140°  when  they 
are  in  a  dry  medium,  100°  when  they  are  moist. 

The  temperature  of  predilection  of  microbes  is  from 
20°  to  39° ;  above  the  latter  temperature  disturbances 
of  microbic  activity,  either  temporary  or  permanent, 
are  liable  to  ensue  (principle  of  attenuation  by  heat). 

Cold  arrests  the  multiplication  of  microbes  (latent 
life),  but  kills  them  only  with  difficulty.  Some  have 
been  exposed  to  a  temperature  of — 105°  without  their 
vitality  being  completely  destroyed. 

c)  Light. — Light  is  a  puissant  cause  of  destruction 
to  microbes ;  it  excites  oxidation  of  their  constituent 
principles  and  especially  of  the  hydro-carbonaceous 
substances ;  its  action  is  quite  rapid  and  continues  even 
after  the  germs  are  again  removed  from  the  light. 

d)  Electricity. — The   action   of  continuous   and   of 


Physiology  of  Microbes.  29 

induction  currents  have  been  studied.     This  action. 


however,  is  but  little  known ;  in  the  case  of  continu- 
ous currents  it  is  necessary  to  take  into  account  the 
electrolysis  which  separates  the  acids  from  the  bases 
and  transfers  these  new  molecules  to  the  two  poles. 
The  acid  reaction  of  the  positive  pole  is  opposed  to 
microbic  pullulation  at  this  point;  the  alkalinity  of 
the  negative  pole  is  less  energetic  in  its  action.  The 
current  may  act  upon  the  germ  itself  and  interfere 
with  its  multiplication,  especially  when  strong  cur- 
rents are  employed.  It  is  not  inadmissible  to  hope 
that,  the  influence  of  electricity  becoming  better 
known,  its  effects  may  some  day  be  utilized  in  the 
treatment  of  infectious  diseases. 

3.  Chemical  influences. — The  exhaustion  of  the  nu- 
tritive medium,  accumulation  of  residual  products, 
excess  of  alkalinity  and  more  especially  of  acidity, 
oppose  and  may  even  arrest  the  multiplication  of 
germs. 

Certain  chemical  substances  exert  toxic  effects  upon 
microbes,  this  toxicity  varying  with  the  microbic 
species  concerned.  The  rational  application  of  this 
action  constitutes  the  basis  of  antisepsis  from  which 
hygiene  and  medicine  have  already  derived  great 
profit. 

4.  Physiological  influences. — "When  several  microbic 
species  occur  in  the  same  place  they  may  oppose  each 
other  and  then  a  veritable  struggle  for  existence  en- 
sues. From  this  concurrence  may  result  the  annihila- 
tion of  the  least  favored  species;  the  medium,  the 
number  of  germs,  and  various  other  circumstances 
may  intervene  here.     In  putrefactive  media  in  which 


30  Manual  of  Veterinary  31kroUology. 

tlie  bacterium  termo  and  bacillus  subtilis  live  we  do 
not  find  the  bacillus  septicus. 

Under  other  circumstances  it  may  happen  that  the 
two  associated  germs  assist  each  other,  the  one  pre- 
paring alimentary  materials  for  the  other,  or,  it  may 
ije,  protecting  the  other  from  the  noxious  action  of 
certain  agents  (association  of  aerobic  and  anaerobic 

germs). 

We  ous"bt  to  mention  in  this  connection  the  influ- 
ence  exerted  upon  microbes  by  the  tissue  elements  of 
animals  in  which  they  sometimes  live  (phagocytosis); 
we  will  enter  more  into  the  details  of  this  subject  in 
the  second  part. 

VII.  Action  of  microbes  upon  the  media. 

1.    ROLE  OF  THE  BACTERIA  IN  NATURE. 

From  a  general  biological  point  of  view  the  role  of 
microbes  consists  in  reducing  to  the  condition  of  sim- 
ple inorganic  compounds  the  organic  matter  built  up 
by  vegetables  and  incorporated  by  animals.  The  dis- 
assimilation  which  occurs  in  these  beings  correlative 
with  nutrition  destroys  a  part  of  this  organic  matter 
and  reduces  it  to  the  condition  of  carbonic  acid, 
water,  and  salts.  This  constantly  occurring  decom- 
position, however,  not  only  fails  to  completely  min- 
eralize the  substance  upon  which  it  acts,  but,  in  addi- 
tion, at  the  death  of  animals  and  plants  an  amount 
of  elaborated  substance  remains  which,  in  future,  is 
exempt  from  this  cause  of  destruction.  It  is  here 
that  microbes  or,  more  accurately,  ferments  enter  on 
the  scene. 

"  The  life  of  the  larger  forms  of  vegetation  builds 


Physiology  of  Microbes.  31 

up  in  nature  at  the  expense  of  the  solar  heat,  sub- 
stances whose  production  requires  a  certain  expendi- 
ture of  force.  It  is  in  these  endothermlc  subtances 
that  the  lower  organisms  implant  themselves.  From 
the  energy  which  they  find  there  stored  up  they  bor- 
row a  portion  for  the  construction  of  their  own  tis- 
sues, which  renders  them  up  to  a  certain  point  inde- 
pendent of  external  conditions.  Another  portion  is 
used  to  convert  into  the  gaseous  condition  substances 
originally  fluid  or  solid.  Another,  finally,  is  trans- 
formed into  sensible  heat  and  serves  to  elevate  the 
temperature  of  the  fluid  in  which  all  these  phenomena 
occur,  and,  as  a  consequence,  to  accelerate  their  pro- 
duction."    (Duclaux.) 

To  accomplish  this  immense  work  the  ferments  are 
endowed  with  an  intense  destructive  power,  and  ope- 
rate, thanks  to  the  rapidity  of  their  multiplication,  in 
innumerable  legions. 

We  must  here  briefly  refer  to  fermentations  and 
putrefaction. 

Fermentations. — Fermentations  are  always  the  result 
of  the  intervention  of  micro-organisms.  They  consist 
in  modifications  of  special  organic  substances  tending 
to  the  formation  of  simpler  products  in  which  the  heat 
of  total  combustion  is  less  than  that  of  the  ferment- 
able substances  from  which  they  are  derived.  The 
difference  between  these  quantities  of  heat  represents 
the  amount  of  energy  appropriated  by  the  germ  for 
its  nutritive  requirements,  and  the  reaction  by  which 
the  fermentation  is  characterized  has  no  other  object 
than  the  liberation  of  this  energy. 

Fermentable  substances  are  comparatively  few  in 
number ;  they  are  usually  bodies  rich  in  oxygen — 


32  Manual  of  Veterinary  Microbiology. 

carbo-hydrates,  polyatomic  alcohols,  the  lower  fatty 
acids,  and  albuminoids.  According  to  the  substance 
predominating  in  their  products,  fermentations  are  de- 
scribed as  alcoholic,  acetic,  lactic,  butyric,  viscous, 
ammoniacal,  etc. 

Microbes  capable  of  developing  fermentations  are 
called  zymogenic. 

Putrefaction. — By  putrefaction  is  meant  the  decom- 
position of  the  substance  of  organized  beings  through 
the  agency  of  microbes.  This  decomposition  super- 
venes shortly  after  death  ;  exceptionally  it  is  observed 
during  life  as  we  will  see  in  the  special  part  of  this 
work.  The  microbes  which  determine  it  are  called 
septogenic.  It  consists  in  a  series  of  fermentations  so 
associated  that  the  products  of  the  one  form  the  point 
of  departure  for  the  following.  These  fermentations 
occur  simultaneously  and  take  eifect  upon  the  various 
immediate  principles  of  the  organism :  albuminoid 
substances,  hydrocarbonaceous  bodies,  etc. 

But  the  decomposition  of  these  last  named  princi- 
ples giving  rise  to  fermentations  simpler  and  better 
known,  and  specially  denominated  as  such,  the  term 
putrefaction  refers  more  particularly  to  the  microbic 
degradation  of  albuminoid  molecules. 

Many  microbic  species  are  concerned  in  putrefac- 
tion, these  species  varying  according  to  the  case  ;  there 
are  some  which  are  quite  frequently  met  with,  such 
as  bacterium  termo,  bacillus  subtilis  (hay  bacillus),  and 
bacillus  septicus,  micro-germs  whose  characteristics  will 
be  indicated  later,  we  always  meet  with  an  association 
of  aerobic  and  anaerobic  organisms. 

The  bodies  which  arise  during  putrefaction  are  nu- 
merous :  hydrogen,  sulfuretted,  carburetted  and  phos- 


Physiology  of  Microbes.  33 

phoretted  hydrogen ;  ammonia,  carbonic, formic,  acetic, 
butyric,  and  lactic  acids,  etc.;  amines,  trimethylamin, 
propylamin,  etc.;  indol,  scatol,  tyrosin,  ptomaines,  etc. 
The  term  saprogenic  is  apphed  more  particularly  to 
those  microbes  which  excite  putrefaction  with  disen- 
gagement of  a  peculiarly  fetid  odor. 

2.    EOLE    OF   BACTERIA   EST   THE   NORMAL   ORGANISM. 

In  a  general  way  the  microbes  which  live  within  or 
upon  healthy  individuals  behave  as  commensals  with- 
out giving  rise  to  the  slightest  disturbance  in  their 
host. 

Nevertheless,  as  there  are  almost  always,  among  the 
germs  distributed  on  the  normal  organism,  a  certain 
number  which  are  pathogenic,  we  can  understand  that 
their  presence  constitutes  a  permanent  source  of  dan- 
ger for  the  economy.  This  danger  exists  upon  all 
contaminated  surfaces  the  germs  being  able  to  invade 
the  organism  when  an  accidental  abrasion  occurs. 

Digestive  action. — The  germs  lodged  within  the  di- 
gestive canal  have  a  more  interesting  role,  for  they  seem 
to  place  themselves  at  the  service  of  their  host  in 
order  to  assist  in  the  preparation  of  his  foods,  in  his 
digestion.  Bienstock  has  isolated  from  faeces  a  bacil- 
lus which  converts  albumen  into  peptones;  the  bacil- 
lus amylobacter,  which  is  found  in  the  stomach  of 
ruminants,  secretes  a  soluble  ferment  which  acts  upon 
starch  and  cellulose. 

M.  Abelous  has  collected  from  the  stomach  sixteen 
species  of  microbes  whose  resistance  to  the  action  of 
the  gastric  juice  he  has  verified.  The  study  of  their 
digestive  action  gave  very  interesting  results.  Albu- 
men, casein,  fibrin  and  gluten  were  rapidly  and  com- 


34  Manual  of  Veterinary  Microbiology. 

pletely  peptonized  by  several  of  them.  Cane  sugar 
was  inverted  by  eight  different  species.  Eleven  species 
more  or  less  completely  converted  starch  into  sugar. 
The  conjoined  action  of  these  different  micro-organ- 
isms upon  a  complex  food  must  be  considerable. 

Putrefaction  of  dead  bodies. — The  healthy  intestinal 
mucosa  forms  an  effective  barrier  to  the  invasion  of 
germs  pullulating  within  the  intestine;  after  death  the 
cells  having  lost  their  power  of  resistance  are  rapidly 
dissolved  by  the  diastases  which  these  microbes  secrete, 
and  the  latter  penetrate  within  the  tissues.  They  are 
first  found  in  the  peritoneum  and  on  the  surface  of  the 
abdominal  viscera;  they  multiply  in  the  blood  of  the 
mesenteric  veins  and  extend  along  the  portal  vein, 
from  which  they  progress  toward  the  heart ;  thus,  in 
various  ways,  they  more  or  less  rapidly  invade  the 
whole  economy. 

These  anaerobic  germs  find  in  the  organism  deprived 
of  oxygenated  blood  the  most  favorable  conditions  for 
their  multiplication.  Hence  putrefaction  is  the  more 
rapid  in  proportion  as  the  blood  is  poorer  in  oxygen 
at  the  time  of  death,  for  example,  in  animals  dead 
from  charbon.  In  some  cases  the  lack  of  oxygen  is 
seconded  by  the  absence  of  coagulation  of  the  blood 
and  of  cadaveric  rigidity,  conditions  which,  by  main- 
taining the  fluidity  of  the  medium,  render  microbic 
invasion  more  easy. 

Putrefaction  of  cadavers  is,  therefore,  primarily  the 
effect  of  anaerobic  germs  coming  from  the  intestinal 
surface;  the  anaerobes  of  other  surfaces  are  in  fact 
paralyzed  in  most  cases  by  contact  with  the  oxygen 
of  the  atmosphere.  Putrefaction  differs  somewhat  ac- 
cording to  the  surroundings  in  which  it  occurs. 


Physiology  of  Microbes.  35 

Putrefaction  in  the  air. — The  multiple  fermentations 
developed  by  microbes  cause  softening  of  the  paren- 
chyma, dissolution  of  the  blood  globules,  infiltration 
of  coloring  matters  in  dependent  parts,  gaseous  disen- 
gagements wliich  permeate  the  connective  tissue  and 
elevate  the  skin,  bloating,  swelling  of  various  parts  of 
the  body,  rupture  of  the  surfaces  and  oozing  of  sani- 
ous  fluids.  We  then  find  aerobic  germs  implanting 
themselves  in  these  fluids,  consuming  by  the  aid  of 
the  oxygen  of  Ihe  air  the  products  of  anaerobic  fer- 
mentations, and  thus  completing  the  mineralization 
of  the  organic  substance. 

Such  are  the  phenomena  which  supervene  in  bodies 
left  in  the  air ;  they  reduce  these  bodies  to  pulp  in  a 
few  weeks,  more  or  less  rapidly  according  to  the  tem- 
perature. 

Putrefaction  under  water. — In  water,  anaerobes  only 
come  into  play;  in  running  waters  the  surface  of  the 
cadaver  is  constantly  being  washed  and  superficial 
microbic  invasion  thereby  prevented.  On  account  of 
the  preservation  of  the  elasticity  of  the  skin  by  con- 
stant bathing  the  swelling  is  more  intense  and  more 
uniform.  The  accumulation  of  gases  causes  the  body 
to  float,  and  the  blood  accumulates  in  the  dependent 
parts,  in  which  alone  cadaveric  patches  are  produced. 

Putrefaction  in  the  soil. — Burial  of  a  cadaver  in  a 
porous  and  absorbent  soil  is  followed  by  absorption 
by  the  latter  of  the  organic  fluids  as  they  are  pro- 
duced. From  this  results  a  comparative  desiccation 
which  maintains  a  certain  degree  of  consistence  in  the 
body  and  interferes  with  microbic  puUulation,  whilst 
it  favors  the  invasion  of  fungi.  Hence,  we  see  the 
development  of  molds  (penicillium,  aspergillus,  etc.) 


36  llanual  of  Veterinary  Microbiology . 

wliich  excite  a  more  complete  combustion  of  organic 
matter;  on  the  other  hand,  the  dissemination  in  the 
soil  of  the  fluid  products  of  putrefaction  renders  the 
action  of  the  anaerobic  germs  more  general. 

From  a  practical  point  of  view  these  facts  ought  to 
be  taken  into  account,  as  their  rational  application 
enables  us  to  limit  the  intervention  of  microbes  in 
putrefaction,  several  of  which  possess  pathogenic  prop- 
erties and  the  emanations  from  which  are  in  all  cases 
to  be  avoided.  The  earth-system  (burial  of  the  cadaver 
in  furnace-dried  earth)  realizes  the  ideal  from  this 
point  of  view. 

Putrefaction  is  always  slower  in  water  and  in  the 
soil  on  account  of  the  lower  temperature  of  these 
media. 

3.  Role  in  the  organism  in  the  pathological  condi- 
tion. 

A  certain  number  of  microbes  which  meet  with 
conditions  favorable  to  their  development  within  the 
organism  of  animals  are  the  determining  cause  of  dis- 
eases in  these  animals.  These  diseases  are  most  fre- 
quently contagious.  The  pathogenic  property  of  a 
microbe  is  a  functional  attribute  of  its  vital  faculties ; 
in  other  words,  it  is  to  the  life  of  the  germ,  to  its 
nutritive  requirements,  to  its  secretions  and  excretions, 
and  to  its  multiplication,  that  we  must  ascribe  the  dis- 
turbances which  it  determines.  The  study  of  patho- 
genic microbes,  the  principal  object  of  this  work,  will 
be  considered  in  the  second  and  third  parts. 


Physiology  of  3Iicrobes.  37 

VII.   Classification. 

Cohn  has  proposed  to  class  the  bacteria  among  the 
lower  algffi.  Previously  they  were  generally  con- 
sidered as  fungi.  Several  classifications  of  microbes 
have  been  proposed,  none  of  which  are  perfect;  we 
reproduce  that  of  M.  Guignard.  The  grouping  of 
bacteria,  however,  has  but  little  importance  from  our 
point  of  view.  JS'evertheless,  it  will  assist  the  reader 
to  a  correct  understanding  of  the  meaning  ascribed  to 
certain  terms  in  common  use. 


38 


Manual  of  Veterinary  Microbiology. 


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Pathogenic  Microbes  in  the  Static  Condition.        39 


PAKT   SECOND. 

GENERAL  CONSIDERATIONS  UPON  PATHOGENIC 

MICROBES. 

This  secona  part  of  our  work  will  embrace  :  1st.  the 
study  of  pathogenic  microbes  in  the  static  condition, 
that  is  to  say,  considered  especially  as  to  their  general 
localizations,  without  taking  into  consideration  their 
action  upon  the  economy ;  2d.  the  study  of  the  recip- 
rocal reaction  of  the  organism  and  the  microbe,  which 
we  will  designate  by  the  term  physiology  of  pathogenic 
microbes ;  3d.  the  transformations  and  destruction  of 
microbes  in  their  relations  with  hygiene  and  therapeu- 
tics, and  4th.  finally,  the  methods  of  determination  of 
pathogenic  microbes. 


CHAPTER  I. 


PATHOGENIC    MICROBES   IN    THE    STATIC    CONDITION. 

1.  Conditions  of  life  in  external  media  and  within  the  economy. 
Sources  of  infection. — 2.  Distribution  of  pathogenic  germs.— 
3.  Modes  of  contagion.  Ways  of  penetration  of  pathogenic 
microbes. 

Most  micro-organisms  live  in  the  external  world  at 
the  expense  of  dead  matter ;  these  have  received  the 
name  of  saprogenic  or  saprophytic  germs. 

Some  live  in  either  a  permanent  or  adventitious  way 


40  Manual  of  Veterinary  Microbiology. 

upon  animals  and  mankind  ;  they  are  called  pathogenic 
when,  by  their  pullulation,  they  give  rise  to  diseases. 
These  afi'ections  have  long  been  known  but  the  study 
of  their  causes,  the  infinitely  little,  is  of  quite  recent 
date ;  such  diseases  are  called  infectious.  Later,  we 
will  have  to  distinguish  infections  properly  so  called 
from  intoxications  of  microbic  origin. 

The  term  virulence  is  applied  to  the  collection  of 
properties  by  which  pathogenic  microbes  are  able  to 
prove  detrimental  to  living  beings.  This  faculty  is 
far  from  being  unchangeable  ;  it  may  present  all  de- 
grees of  intensity,  in  accordance  with  conditions  ca- 
pable of  modifying  the  vitality  of  the  germ. 

The  term  virus  is  applied  to  solid,  liquid,  or  gaseous 
vehicles  containing  pathogenic  germs. 

I.  Conditions  of  life  of  pathogenic  germs    in    external 
media  and  within  the  living  organism. 

Those  germs  which  cause  diseases  do  not  exclusively 
and  necessarily  live  within  the  economy.  Some  of 
them  can  also  multiply  in  dead  organic  media ;  others, 
indeed,  only  pullulate  within  the  organism  incidentally 
the  external  media  being  really  their  natural  field  of 
multiplication. 

In  accordance  with  these  considerations  pathogenic 
germs  have  been  divided  into  three  categories  : 

a.  Contagious  obligatory  parasites ; 

b.  Contagious  facultative  parasites  ; 

c.  Non-contagious  facultative  parasites. 

Contagious  obligatory  parasites. — These  are  repre- 
sented by  microbes  which,  under  natural  conditions, 
only  reproduce  themselves  in  the  living  organism  and 
are  transmitted  from  one  animal  to  another  without 


Pathogenic  Microbes  of  the  Static  Condition.        41 

undergoing  any  evolution  in  the  surrounding  media. 
Of  these,  two  varieties  are  distinguished  ;  1st.  those 
which,  little  resistant,  perish  immediately  on  leaving 
the  organism,  and  the  transmission  of  which  must  be 
made  directly  by  contact  of  a  diseased  subject  with  a 
healthy  subject :  syphilis,  gonorrhoea,  rabies ;  2d.  those 
which,  more  resistant,  are  preserved  for  a  certain  timje 
outside  of  the  economy,  without  however  multiplying, 
and  may  arrive  upon  healthy  subjects  by  means  of  vari- 
ous vehicles,  contact  with  a  diseased  subject  not  being 
absolutely  necessary  :  measles,  variola,  scarlatina,  diph- 
theria, glanders,  tuberculosis.  In  this  case  the  source 
of  the  contagious  disease  resides  principally  but  not 
exclusively  in  the  diseased  organism.  If  the  germ  is 
met  with  elsewhere  it  will  be  upon  objects  which  have 
been  in  direct  relation  with  the  diseased  or  its  cada- 
ver ;  these  objects  can,  moreover,  communicate  the 
latent  germs  of  which  they  are  bearers  to  the  ordinary 
media :  soil,  water,  or  air,  in  which  these  germs  pre- 
serve their  contagiousness  for  a  period  of  time  more 
or  less  extended. 

Whatever  variations  there  may  be  in  the  mode  of 
contagion,  the  contagious  obligatory  parasite  arrives 
upon  the  healthy  organism  in  the  same  condition  in 
which  it  left  the  diseased  subject  where  it  had  its 
origin. 

Contagious  facultative  parasites. — These  live  and 
multiply  not  only  within  the  organism  of  animals,  but 
also  outside  of  the  latter,  upon  dead  organic  matters, 
in  waters,  etc.;  germs  of  pysemia,  septicaemias,  gan- 
grene, erysipelas,  typhoid  fever,  asiatic  cholera. 

The  virulence  of  some  of  these  germs  seems  even 
to  be  diminished  by  their  passage  through  the  organ- 


42  Manual  of  Veterinary  Microbiology. 

ism  to  such  a  degree  that  the  disease  quickly  dies  out 
if  their  original  virulence  is  not  restored  by  a  return 
to  the  outer  media ;  it  is  thus  with  cholera,  for  exam- 
ple, which  spontaneously  disappears  in  winter  in  the 
countries  of  central  Europe,  probably  because  the  ex- 
ternal media  have  become  unsuitable  to  its  multipli- 
cation. In  the  case  of  cholera  we  perceive  a  grada- 
tion toward  the  miasms  ;  but  whilst  in  this  last  the 
microbe  exhausts  its  effects  upon  the  individual  which 
harbors  it  and  does  not  extend  beyond  it,  the  bacillus 
of  cholera,  on  the  contrary,  proliferates  during  its  pass- 
age through  the  organism  of  man  and  thus  increases 
the  chances  of  later  infection. 

The  source  of  infection,  therefore,  for  germs  of  this 
kind  is  twofold :  the  diseased  organism  and  the  in- 
fected media  in  which  the  germs  pullulate;  these  two 
sources  possess  in  the  same  degree  the  power  of  be- 
getting the  disease,  and  the  opportunities  of  infection 
will  be  more  frequent  than  for  the  germs  of  the  first 
group  in  as  much  as  the  multiplication  of  the  microbes 
in  the  different  media  is  an  important  cause  of  their 
preservation. 

Non-contagious  facultative  imrasites. — These  live,  in 
the  normal  condition,  in  the  external  media,  and  it  is 
only  incidentally  that  they  develop  within  the  organ- 
ism of  animals.  They  do  not  seem  in  the  latter  to 
meet  with  conditions  favorable  to  their  vitality,  for 
their  effects  are  exhausted  completely  in  the  course  of 
the  disease  which  they  determine,  and  the  disease  is 
not  transmitted  from  one  subject  to  another.  The 
condition  under  which  it  occurs  consists  always  in  the 
impregnation  of  a  healthy  organism  by  germs  drawn 
directly  from  external  infected  media ;  in  short,  the 


Pathogenic  3Iicrobcs  in  the  Static  Condition.       43 

disease  is  bound  to  the  soil :  paliidic  fevers,  perhaps 
yellow  fever. 

The  three  classes  of  germs  which  we  have  just  been 
considering  explain  the  distinction  formerly  made  be- 
tween the  different  forms  of  virus.  The  first  corre- 
sponds to  contagions,  the  second  to  miasmatic-contagions, 
and  the  third  to  the  miasms  j^roj^erly  so  called. 

Usually  we  also  class  with  the  miasms  the  toxic 
gases  which  are  disengaged  from  cesspools,  and  the 
poison  of  the  expired  air. 

Baumgarten  has  divided  pathogenic  microbes  into 
exogenous  and  endogenous,  according  to  whether  they 
come  from  the  exterior  or  from  the  diseased  subjects 
themselves. 

II.  Distribution  of  ^pathogenic  germs. 

A  certain  number  of  pathogenic  germs  are  ubiquit- 
ous in  nature;  we  meet  with  them  almost  every- 
where. Such  is  the  case  with  the  germs  of  suppura- 
tion and  of  septicsemias,  on  account  of  their  excessive 
production  and  the  readiness  with  which  they  live  in 
the  surrounding  media.  Specific  germs  are  only  in- 
cidentally found  in  such  media. 

In  the  following  lines  we  will  review  in  succession 
the  various  media  which  may  contain  germs  noxious 
for  the  economy,  this  study  being  essential  to  a  cor- 
rect understanding  of  the  diflferent  methods  of  con- 
tagion. 

Air. — We  have  seen,  in  the  first  part,  that  the  air 
can  hold  germs  in  suspension  ;  it  is  natural  to  think 
that  among  these  we  may  find  some  which  are  pos- 
sessed of  pathogenic  properties.  Moreover,  it  can 
readily  be  understood   that  the  dust  of  the   streets 


44  Manual  of  Veterinary  Microbiology. 

and  accumulations  of  dirt  will  yield  to  the  atmos- 
phere, under  the  influence  of  numerous  agitations 
of  the  air,  particles  contaminated  with  pathogenic 
germs,  which  may  have  been  brought  there  in  various 
ways. 

It  was  for  a  long  time  believed  that  the  air  expired 
by  the  diseased  was  a  fertile  cause  of  the  diffusion  of 
pathogenic  germs  in  the  atmosphere,  but  we  now 
know  that  the  expired  air  never  contains  germs, 
neither  have  we  succeeded  in  transmitting  diseases  in 

this  way. 

Transmission  by  the  air  has  been  accomplished  ex- 
perimentally for  a  certain  number  of  diseases  (sheep- 
pox,  charbon,  tuberculosis,  vaccinia,  etc.)  by  the  dis- 
semination of  the  dried  virus  of  these  diseases  in  the 
atmosphere. 

Under  natural  conditions  the  atmospheric  germs 
occur  in  a  state  of  great  dilution  and  hence  the 
chances  of  infection  are  extremely  limited.  If  we  add 
that  the  air  lends  itself  little  or  not  at  all  to  their 
multiplication,  and  that  they  are  destroyed  more  or 
less  rapidly  by  light,  oxygen,  and  dessication,  we  shall 
see  that  the  danger  from  the  free  atmosphere  is  al- 
most nil. 

The  confined  atmosphere  of  inhabited  houses  con- 
tains more  germs  than  the  external  air,  that  of  cities 
more  than  that  of  the  country. 

The  confined  atmasphere  of  infected  places  can  be- 
come the  carrier  of  disease  germs  and  can  transmit 
certain  contagious  diseases  either  by  transporting 
these  germs  into  the  respiratory  passages,  or  by  de- 
positing them  upon  alimentary  matters  or  on  the  sur- 
face of  wounds.     The  pyogenic  microbes  have  been 


Pathogenic  3Iicrobes  in  the  Static  Condition.       45 

met  with  in  surgical  wards,  the  bacillus  of  Kocli  in 
those  of  the  tuberculous.  These  germs  come  from  the 
dried  exudates,  dressing  cloths,  etc. 

It  is  therefore  necessary,  in  places  where  diseased 
subjects  reside,  to  take  precautions  against  the  germs 
of  the  atmosphere. 

The  condition  of  desiccation  of  virulent  material 
has  necessarily  a  great  influence  upon  the  richness  of 
the  air  in  pathogenic  products,  and  all  the  conditions 
which  assist  in  raising  the  dust  are  of  such  a  nature 
as  to  increase  the  number  of  these  products.  Klebs 
has  observed  that  during  an  epidemic  of  diphtheria  a 
large  number  of  new  cases  occurred  after  the  sweep- 
ing of  the  streets  and  that  they  especially  prevailed 
along  the  roads  followed  by  the  wagons  used  in  trans- 
porting the  dirt. 

Waters. — From  a  pathological  point  of  view,  gen- 
erally speaking,  a  water  is  the  more  to  be  feared  the 
greater  the  proportion  of  organic  matter  it  contains, 
since  this  material  implies  the  presence  of  microbes 
which  live  at  its  expense.  Most  of  the  germs  of 
water,  however,  are  inoffensive;  only  rarely  have 
pathogenic  microbes  been  met  with :  septic  vibrio,  pus 
cocci,  etc. 

Pathogenic  germs  find  entrance  to  waters  in  various 
ways ;  they  may  come  from  the  air,  from  the  bodies 
of  animals  which  have  succumbed  to  infectious  dis- 
eases, or  they  may  come  from  the  soils  traversed  by 
the  waters.  This  last  mode  has  especially  attracted 
attention  during  recent  times  :  the  bacillus  of  typhoid 
fever  of  man  which  is  voided  with  the  fsecal  matters, 
can  pass  with  the  liquids  of  cesspools  through  very 
porous  soils  and  thus  come  to  contaminate  the  subter- 


46  Manual  of  Veterinary  Microbiology. 

ranean  waters.  When  these  waters  are  used  for  hu- 
man consumption  an  epidemic  of  typhoid  fever  may 
result.  The  knowledge  of  this  fact  has  enabled  us  in 
numerous  cases  to  trace  the  disease  to  its  source  and 
check  its  extension.  The  bacillus  of  cholera  is  dis- 
seminated in  the  same  manner. 

Generally  speaking,  therefore,  waters  charged  with 
organic  matters  should  be  viewed  with  suspicion,  and 
it  is  necessary  to  take  particular  precautions  in  order 
to  avoid  the  pollution  of  alimentary  waters  by  cess- 
pools, dung-hills,  trenches  of  liquid  manure,  by  the 
stagnant  waters  of  the  streets,  etc. 

The  vicinity  of  these  reservoirs  of  organic  detritus 
to  the  sources  of  alimentary  waters  is  always  to  be 
dreaded,  especially  when  the  earth  is  little  adapted  to 
filtration ;  hence,  it  is  preferable,  especially  in  thickly 
populated  centers,  to  secure  water  which  has  filtered 
through  virgin  soils  and  convey  it  to  the  cities  by  a 
system  of  closed  canals. 

Pathogenic  bacteria  preserve  their  virulence  in 
water  for  varying  periods.  It  has  been  observed  that 
this  virulence  is  preserved  during  four  months  for  the 
bacillus  of  charbon,  one  year  for  its  spores;  the  bacillus 
of  typhoid  fever  retains  its  vitality  for  two  months  in 
water,  that  of  cholera  for  twenty-four  hours  in  cess- 
pools, and  twenty-nine  days  in  spring  water;  those  of 
glanders  and  tuberculosis  for  twenty  and  ten  days  re- 
spectively (in  water). 

Soil. — The  germs  of  the  soil  are  numerous,  their 
function  being  to  transform  organic  matters  of  which 
this  medium  is  the  great  recipient ;  but  most  of  them 
are  without  efiect  on  the  organism  of  animals,  Never- 
theless, inoculation  of  vegetable  mold  into  the  small 


Pathogenic  3Iicrohes  in  the  Static  Condition.        47 

animals  of  the  laboratory  often  rapidly  leads  to  death 
with  suppuration  or  gangrene  as  local  lesions.  Wounds 
contaminated  by  the  soil  readily  become  complicated 
by  accidents  of  the  same  kind. 

The  specific  germs  which  are  incidentally  met  with 
in  the  soil  are  those  of  tetanus,  charbou,  Pasteur's 
septicsemia,  typhoid  fever,  cholera,  etc. 

Germs  are  especially  abundant  in  the  superficial 
layers  of  the  soil.  The  almost  constant  humidity  of 
the  soil  in  winter  carries  them  into  the  deep  layers ; 
on  the  other  hand,  during  periods  of  drought,  in 
the  absence  of  descending  currents  of  water,  the  su- 
perficial washing  is  less  complete  and  the  germs  re- 
main more  in  the  layers  in  contact  with  the  atmosphere. 
Thus,  other  things  being  equal,  the  dust  will  be  richer 
in  germs  in  summer  than  in  winter. 

The  micro-organisms  of  the  soil  become  harmful  in 
various  ways  :  1st.  by  contaminating  the  vegetable 
foods  which  grow  upon  an  infected  place ;  2d.  by 
distributing  themselves  in  the  air  through  the  desicca- 
tion of  the  soil ;  3d.  by  directly  contaminating  a  so- 
lution of  continuity  (tetanus) ;  4th.  by  contaminating 
the  waters  which  filter  through  the  earth  and  which, 
later,  are  to  serve  for  alimentation. 

In  the  first  three  cases  the  germs  must  occupy  the 
surface  of  the  arable  laver :  microbes  which  are  more 
deeply  situated  may  return  to  the  surface  by  the  in- 
crease in  height  of  the  sheet  of  subterranean  water, 
by  the  phenomenon  of  capillarity  which  constantly 
occurs  in  finely  divided  soils,  or,  finally,  through  the 
intermediation  of  earth  worms,  larvae,  etc.,  a  fact 
which  has  been  demonstrated  by  M.  Pasteur  in  the 
case  of  charbon. 


48  Manual  of  Veterinary  Microbiology. 

The  infection  of  subterranean  waters  by  tbe  soil  is 
subject  to  numerous  influences  dependent  upon  the 
location  and  nature  of  the  land.  Changes  of  eleva- 
tion of  the  surface  waters  also  produce  effects  which 
it  is  of  importance  to  consider.  It  has  been  noticed 
that  large  floods  are  often  followed  by  typhoid  epi- 
demics, a  circumstance  which  has  been  attributed  to  the 
simultaneous  rise  in  level  of  the  waters  of  infiltration 
generally,  and  especially  adjoining  large  sheets  of 
surface  water;  this  elevation  of  the  subterranean  wa- 
ters brings  them  into  contact  with  soils  impregnated 
with  putrid  matters  in  the  neighborhood  of  cesspools, 
trenches  of  liquid  manure,  sewers,  etc.,  and  when 
these  putrid  matters  contain  the  typhoid  germ  there 
results  a  general  pollution  of  springs  and  wells  into 
which  these  contaminated  waters  difiuse  themselves. 

The  pathogenic  germs  of  the  soil  can  retain  their 
vitality  for  a  period  more  or  less  extended  ;  Grancher 
has  seen  the  typhoid  bacillus  retain  its  vitality  in  the 
soil  for  five  months.  The  charbon  bacillus  is  also  pre- 
served in  this  medium,  more  especially,  however,  in 
the  form  of  spores. 

The  destruction  of  these  germs  is  dependent  upon 
the  action  of  the  oxygen  and  light ;  as  the  conditions 
of  their  puUulation  are  more  delicate  than  those  of 
saprogenic  microbes,  the  presence  of  the  latter  must 
also  be  taken  into  consideration  in  so  far  as  their  ac- 
tive proliferation  more  or  less  rapidly  brings  about  an 
insuflacient  supply  of  nutrition  for  the  pathogenic 
species. 

Foods. — The  vegetable  foods  may  be  contaminated 
by  pathogenic  germs  either  by  contact  with  the  soil 
while  yet  in  growth  (charbon,  actiuomyces),  or,  after 


Pathogenic  Microbes  in  the  Static  Condition.       49 

harvesting,  in  the  storehouses  of  fodders  by  the  air 
of  infected  stables  or  barns,  or  from  direct  contact 
with  sick  animals. 

MM.  Galtier  and  Violet  attribute  to  the  fodder  the 
development  of  the  typhoid  affections  of  the  horse. 

Foods  of  animal  origin  are  sometimes  bearers  of 
pathogenic  germs.  This  is  the  case  when  they  come 
from  subjects  suffering  from  diseases  caused  by  these 
germs.  The  flesh  and  all  the  tissues  of  animals  dead 
from  charbon  contain  the  bacteridium. 

Dwellings  and  vehicles. — Places  which  have  been  oc- 
cupied by  animals  affected  with  contagious  diseases,  and 
vehicles  (wagons,  etc.)  which  have  been  used  in  their 
transportation  are  most  frequently  infected  by  specific 
germs.  These  are  deposited  upon  the  floor,  walls 
and  ceilings  of  houses  and  upon  the  mangers,  racks, 
etc.,  either  by  the  air  or  directly  with  the  secretions  or 
excretions  of  the  sick.  The  transmission  of  microbic 
diseases  through  the  intermediation  of  dwellings  is 
therefore  in  every  way  possible. 

Various  articles  and  utensils. — All  the  articles  and 
utensils  which  are  found  in  places  occupied  by  diseased 
animals  or  which  have  been  employed  in  the  service 
of  the  latter — harness,  blankets,  grooming  instru- 
ments, sponges,  brushes,  curry-combs,  etc.,  litter  and 
manure — may  become  bearers  of  pathogenic  germs 
which  have  been  derived  from  these  animals. 

Healthy  organism. — The  bodies  of  animals  in  health 
are  always  bearers  of  microbes;  but  the  latter  are 
most  frequiently  of  no  importance  from  our  present 
point  of  view.  "We  already  know  that  the  ubiquitous 
pathogenic  germs — those  of  suppuration  and  of  septic 
5 


n 


0  3Ia7iual  of  Veterinary  3Iicrohiology . 


accidents — whicli  are  met  with  almost  every-where — 
must  be  present  on  the  surface  of  the  body  and  even 
in  its  interior,  upon  the  various  mucous  membranes 
and  especially  that  of  the  digestive  canal.  Recently 
the  bacillus  of  tetanus  has  been  discovered  in  the 
fsecal  matters  of  healthy  horses.  The  pneumococ- 
cus — the  pathogenic  germ  of  lobar  pnuemonia  in 
man — ^is  constantly  present  in  the  buccal  mucus  of 
nearly  all  individuals.  The  skin,  the  respiratory  mu- 
cous membrane  and  that  of  the  genitd-urinary  pas- 
sages near  the  openings  communicating  "vvith  the  ex- 
terior, are  likewise  contaminated  with  ubiquitous 
germs. 

The  transmission  of  a  contagious  disease  through 
the  intermediation  of  healthy  individuals,  animals  or 
mankind,  shows  that  pathogenic  micro-organisms 
may  be  present  on  or  in  the  body  without  producing 
disease.  The  methods  by  which  infection  is  produced 
and  the  phenomenon  of  immunity  sufficiently  explain 
this  peculiarity. 

Infected  organism. — The  organism  attacked  by  a 
contagious  disease  harbors  the  microbes  of  the  latter 
in  very  difierent  points  according  to  the  nature  and 
localization  of  that  disease.  It  is  desirable,  for  the 
ends  of  a  rational  prophylaxy,  to  know  the  places  of 
election  of  the  germs  of  the  different  diseases,  and, 
more  especially,  the  seat  of  those  which,  in  being 
eliminated  from  the  economy,  are  able  to  contaminate 
healthy  individuals. 

We  may  meet  with  these  germs  in  the  various 
secretions  flowing  to  the  exterior:  in  the  saliva: 
rabies;  in  the  ftecal  matters:  tuberculosis,  typhoid 
fever,  cholera,  chicken  cholera,  pneumo-enteritis ;  in 


Pathogenic  Microbes  in  the  Static  Condition.       51 

the  expectorations :  tuberculosis,  glanders,  actinomy- 
cosis, sheep  pox;  in  the  urine:  bacterial  hsemoglobinu- 
ria  of  cattle,  tuberculosis,  etc.;  in  the  semen  and  vagi- 
nal mucus:  gonorrhoea;  in  the  secretions  of  wounds: 
glanders-farcy  ulcers,  syphilitic  chancres,  lesions  of 
dourine,  pustules  of  variola  of  the  different  species  of 
animals. 

Hemorrhages  may  occur  through  the  various  pas- 
sages and  thus  distribute  externally  the  germs  which 
are  present  in  the  blood  :  charbon. 

If  germs  do  not  appear  to  be  eliminated  by  the  in- 
tact skin  it  is  none  the  less  true  that  the  latter  is  fre- 
quently soiled  by  pathogenic  germs  emitted  by  the 
diseased ;  these  germs  are  conveyed  to  the  skin 
through  contact  of  the  secretions  or  infected  litters. 

A  subject  affected  with  a  contagious  disease  does 
not  appear  to  be  at  all  stages  of  the  disease  capable 
of  communicating  the  contagion  to  the  same  degree. 
Thus,  in  the  case  of  glanders  and  tuberculosis,  the 
danger  appears  to  be  absent  if  the  softened  lesions  do 
not  directly  communicate  with  the  exterior. 

Cadavers  of  infected  subjects. — The  bodies  of  animals 
dead  of  infectious  diseases  are  fertile  sources  of  patho- 
genic germs;  from  the  stand-point  of  the  alimentary 
hygiene  of  man  it  is  of  great  importance  to  recognize 
the  place  of  election  of  those  germs,  but  the  question 
can  hardly  be  considered  in  a  general  manner. 

As  to  the  duration  of  the  virulence  of  pathogenic 
microbes  in  dead  bodies  left  to  themselves,  it  varies 
greatly  according  to  the  germs  concerned,  but  upon 
this  subject  our  knowledge  is  very  incomplete.  We 
know,  however,  that  in  some  diseases  the  pathogenic 
power  may  persist  for  a  long  time — for  years  in  the 


OF  THF. 


52  3Ianual  of  Veterinary  3Iicrohiology. 

case  of  charbon  and  tuberculosis,  for  example.     It  is 
therefore  necessary  to  carefully  destroy  tliese  bodies. 

m.  3Iodes  of  contagion. —  Ways  of  penetration  of  patho- 
genic microbes. 

Those  germs  which  are  exciters  of  disease,  after 
having  multiplied  in  the  bodies  of  the  first  infected 
animals,  may  be  transported  to  other  animals  and 
thus  propagate  the  disease.  This  transference  of  the 
germs  of  a  disease  from  a  sick  to  a  healthy  individual 
constitutes  contagion. 

1.  Modes  of  contagion.  A  microbic  disease  will  the 
more  surely  be  communicated,  the  contagion  will  have 
greater  opportunity  of  taking  effect,  in  proportion  to 
the  number  of  the  germs  emitted  by  the  diseased.  A 
superficially  situated  disease  will  be  more  readily  trans- 
missible, other  things  being  equal,  than  a  deep  seated 
one ;  a  disease  with  lesions  of  large  extent  will  be 
more  easy  to  communicate  than  one  in  which  these 
are  less  extensive.  The  greater  or  less  duration  of  the 
resistance  of  the  virus  to  the  natural  agents  of  destruc- 
tion is  also  a  condition  upon  which  depends  the  aug- 
mentation or  diminution  of  the  contagion-begetting 
power  of  the  virus. 

The  transference  of  pathogenic  germs  from  a 
diseased  subject  to  a  healthy  subject — contagion — may 
be  direct  or  immediate,  that  is,  the  healthy  subject  ob- 
tains the  germs  of  the  disease  from  the  diseased  ani- 
mal itself,  or  it  may  be  indirect  or  mediate,  the  healthy 
individual  receiving  the  microbes  eliminated  by  the 
diseased,  through  the  intervention  of  external  media. 

Direct  or  immediate  contagion. — Of  this  we  have  to 
distinguish  two  cases  according  as  the  transmission 


Pathogenic  3ficrobes  in  the  Static  Condition.        53 

takes  place  between  two  subjects  independent  of  each 
other  (direct  contact),  or  from  the  mother  to  the  foetus 
(heredity). 

Direct  contact. — Direct  contact  seems  to  be  necessary 
for  a  certain  number  of  diseases:  rabies  (bites),  syph- 
-  ihs,  dourine  (coition),  in  which  the  germs,  conta- 
gious obligatory  parasities,  appear  not  to  maintain 
their  virulence  in  the  surrounding  media.  On  the 
contrarj^,  in  other  diseases  direct  contact  is  not  essen- 
tial, the  microbes  maintaining  their  virulence  outside 
of  the  organism  :  glanders,  tuberculosis,  charbon,  etc. 

Man  becomes  infected  by  direct  contact  when  he 
accidentally  inoculates  himself  in  making  autopsy  on 
bodies  affected  with  glanders,  tuberculosis  or  charbon. 

Heredity. — 'Contagious  diseases  appear  to  be  trans- 
mitted from  the  mother  to  the  foetus  only  by  passage 
of  the  specific  microbes  through  the  placenta.  The 
intervention  of  the  father  in  phenomena  of  this  kind 
is  therefore  indirect,  in  as  much  as  the  disease  with 
which  he  is  affected  must  first  be  transmitted  to  the 
mother,  a  fact  which  is  observed  in  syphilis,  for  ex- 
ample. Here,  therefore,  the  action  of  the  mother  in 
reality  alone  comes  into  play. 

Some  infectious  diseases  are  transmitted  from  the 
mother  to  the  foetus;  these  are  especially  general  af- 
fections and  those  in  which  the  germs  are  able  to  cir- 
culate in  the  blood :  certain  septicsemias,  charbon, 
fowl-cholera,  strangles,  rouget,  tuberculosis. 

The  transmission  seems  to  occur  through  alterations 
of  the  placenta,  such  as  hemorrhages,  specific  lesions 
(tubercles,  etc.),  alterations  which,  indeed,  are  readily 
produced  on  account  of  the  diseased  condition  of  the 


54  Manual  of  Veterinary  Microbiology. 

mother  and  the  tendency  of  the  various  germs  living 
in  the  blood  to  determine  vascular  and  other  lesions. 

Nevertheless,  this  interpretation,  which  certain  ob- 
servations sufficiently  justify,  does  not  explain  all  the 
facts  of  heredity,  and  it  seems  that  a  simpler  mechanism 
intervenes  in  some  cases. 

We  know  that  the  contagious  affections  of  the  geni- 
tal apparatus  of  the  female  are  readily  transmissible, 
and  they  will  actually  be  transmitted  to  the  foetus  un- 
less their  existence  renders  gestation  impossible,  or 
provokes  abortion. 

The  disease  transmitted  to  the  foetus  may  cause  the 
death  of  the  latter  and  its  premature  expulsion,  it  may 
disappear,  or,  finally,  may  remain  in  a  stationary  con- 
dition, permitting  the  complete  development  of  the 
young  animal,  in  which,  at  a  later  period,  it  may  un- 
dergo fresh  evolution. 

Hereditary  transmission  may  be  limited  to  the  com- 
munication of  immunity  by  the  diffusion  through  the 
placenta  of  soluble  vaccine  substances  elaborated 
within  the  body  of  the  mother.  But  immunity  in  the 
young  being  may  also  be  consecutive  to  recovery  from 
the  disease  with  which  it  has  itself  been  affected. 

■  Indirect  or  mediate  contagion. — We  call  the  contagion 
indirect  when  the  virulent  germs  which  come  from 
diseased  subjects  are  transported  on  to  healthy  indi- 
viduals after  having  been  deposited  on  its  surround- 
ings. We  have  already  seen  in  considering  the  dis- 
tribution of  pathogenic  germs  in  external  media,  that 
they  may  be  encountered  in  the  air,  water,  the  soil, 
foods,  the  walls  of  houses,  on  mangers,  racks,  manure, 
litter,  and  the  various  objects  and  utensils  which  have 
been  more  or  less  directly  in  contact  with  the  diseased. 


Pathogenic  3Iicrobes  in  the  Static  Condition.       55 

!N"ow,  these  are  just  the  infected  vehicles  which  trans- 
port the  pathogenic  germs  to  healthy  individuals. 

Indirect  contagion  only  occurs  with  facultative 
parasitic  germs  and  with  contagious  obligatory  para- 
sitic germs  which  are  endowed  with  considerable 
power  of  resistance  against  external  causes  of  de- 
struction. 

The  point  of  entry  of  microbes  mediately  trans- 
mitted is  variable;  when  the  virulent  matters  are 
brought  into  contact  with  the  skin,  or  with  the 
genito-urinary  or  ocular  mucous  membranes,  it  is 
called  transmission  by  indirect  contact;  when  the  con- 
tagion is  introduced  with  the  food,  water,  or  by 
the  air,  it  is  called  transmission  by  ingestion  or  inhala- 
tion. 

When  pathogenic  germs  are  once  deposited  on  or 
within  the  organism,  the  manner  in  which  they  may 
affect  the  latter  will  differ  according  to  the  case; 
sometimes  they  will  have  no  appreciable  effect;  at 
other  times  they  may  determine  the  irruption  of  a 
disease  similar  to  that  which  has  engendered  them. 
The  placing  in  activity  of  the  pathogenic  faculty  de- 
pends in  reality  upon  many  circumstances,  and,  in 
the  first  place,  upon  absorption.  We  will  study  here 
the  ways  and  processes  of  absorption  of  pathogenic 
microbes,  as  a  sequel  to  the  study  of  modes  of  con- 
tagion. 

2.  Absorjption  of  pathogenic  microbes. — Disease  germs 
are  capable  of  penetration  through  various  surfaces, 
natural  or  artificial;  these  we  will  now  review  in  suc- 
cession. 

Skin. — The  intact  sKn  is  an  unfavorable  surface 
for  the  absorption  of  germs,  but  does  not  oppose  it- 


56  Manual  of  Veterinary  Microbiology. 

self  in  an  absolute  manner  to  their  penetration  ;  some 
of  them  are  probably  able  to  introduce  themselves 
into  its  substance  through  the  pilo-sebaceous  glands, 
and  thus  give  rise  to  diseases.  The  anatomical  pus- 
tules which  develop  upon  the  hand  or  arm  of  anato- 
mists, surgeons,  and  accoucheurs,  seem  to  be  pro- 
duced in  this  way ;  it  is  the  same  with  acne. 

Repeated  frictions  of  the  skin  at  the  time  of  con- 
tact with  virulent  matters  will  considerably  further 
penetration.  Garre  induced  the  formation  of  furun- 
culous  pustules  on  his  own  arm  by  rubbing  it  with  a 
culture  of  staphylococcus  pyogenes  aureus. 

The  incorporation  of  the  virus  with  a  fatty  body, 
by  rendering  the  contact  more  complete,  increases 
the  facility  and  certainty  of  absorption  by  the  intact 
skin.  Charbon  and  glanders  have  been  communi- 
cated in  this  way. 

In  short,  if  absorption  by  the  healthy  skin  is  pos- 
sible, it  seems  to  take  place  only  within  narrow  limits. 
It  acquires,  on  the  other  hand,  great  importance 
when  a  traumatism  has  opened  the  way  to  microbes, 
most  of  these  being  capable  of  penetrating  through 
even  the  slightest  solutions  of  continuity  in  the  ex- 
ternal integument. 

Digestive  mucous  membrane. — The  different  structure 
of  this  membrane  in  the  various  parts  of  the  digest- 
ive canal  manifestly  implies  variation  in  its  absorp- 
tive faculty  toward  pathogenic  microbes.  The  lining 
membrane  of  the  anterior  passages  is  little  adapted 
to  their  penetration,  but  this  much  more  readily  oc- 
curs if  one  or  several  accidental  solutions  of  con- 
tinuity exist  in  these  passages.  Experiment  has 
shown   that  the   addition   to   fodders   contaminated 


Pathogenic  llicrobes  in  the  Static  Condition.       57 

with  the  virus  of  charbon,  of  bodies  capable  of  ex- 
coriating the  mucosa  (thistles,  husks  of  barley)  in- 
creases the  mortality  from  this  disease,  but  excoria- 
tions of  the  bucco-pharyngeal  mucosa  are  compara- 
tively common,  and  consequently  it  is  necessary  to 
take  into  account  this  way  of  infection. 

Absorption,  however,  appears  occasionally  to  take 
place  in  this  situation  in  spite  of  the  integrity  of  the 
mucosa,  as,  for  example,  when  we  contaminate  a 
healthy  flock  with  aphthous  stomatitis  by  depositing 
a  little  of  the  saliva  coming  from  diseased  animals  in 
the  mouth  of  other  healthy  animals. 

As  in  the  case  of  the  anterior,  the  mucous  mem- 
brane of  the  posterior  digestive  canal  admits  of  pen- 
etration by  virus  when  it  is  the  seat  of  alterations  in 
its  continuity :  erosions,  ulcerations.  But,  even  when 
it  is  intact,  the  gastro-intestinal  mucous  membrane 
does  not  prevent  the  absorption  of  pathogenic  germs, 
as  numerous  experiments  have  demonstrated.  Char- 
bon, glanders,  tuberculosis,  aphthous  fever,  cholera 
of  fowls,  and,  indeed,  nearly  all  microbic  diseases  can 
be  transmitted  in  this  way.  Nevertheless,  all  sub- 
jects which  ingest  virulent  products  do  not  neces- 
sarily become  infected;  a  certain  number  are  refrac- 
tory to  the  disease;  in  others  the  gastric  juice  kills 
all  the  germs  which  are  introduced,  whilst  in  others, 
again,  absorption  may  not  occur. 

Referring  to  the  microbicidal  action  of  the  gastric 
juice,  we  may  repeat,  that  non-sporulated  bacteria 
are  killed  much  more  rapidly  than  spores  ;  infection 
by  the  latter  is  consequently  infinitely  more  certain  ; 
this  fact  has  been  demonstrated  for  charbon. 

Respiratory  mucous  membrane. — Air  charged  with 


58  Manual  of  Veterinary  3Iicrobiology . 

virulent  dust,  being  inhaled  by  a  healthy  subject,  may 
determine  the  outbreak  of  the  disease,  this  fact  hav- 
ing been  established  for  tuberculosis,  charbon,  gland- 
ers, fowl  cholera,  etc.  The  experimental  injection  of 
microbes  within  the  trachea  gives  the  same  result. 

The  respiratory  mucous  membrane,  therefore,  allows 
itself  to  be  traversed  by  microbes.  Nevertheless,  the 
presence  of  pathogenic  germs  in  the  air  does  not  im- 
ply that  infection  will  necessarily  take  place.  These 
germs  are  generally  deposited  upon  the  mucus  of  the 
anterior  passages  and  are  then  rejected  with  the  prod- 
ucts of  expectoration.  The  fact  that  germs  are  con- 
stantly absent  from  the  expired  air  whilst  they  are 
always  contained  in  the  inspired  air,  sufficiently  shows 
that  the  latter  is  purified  in  contact  with  the  mucous 
membrane. 

Absorption  by  the  respiratory  mucous  membrane 
may  occur  throughout  its  whole  extent ;  as  with  other 
lining  membranes,  this  absorption  is  favored  by  solu- 
tions of  continuity. 

Ocular  mucous  membrane. — The  conjunctival  mu- 
cous membrane  absorbs  certain  microbes;  of  this, 
accidental  inoculation  of  gonorrhoeal  pus  in  the  eye 
furnishes  sufficient  evidence.  M.  Galtier  has  suc- 
ceeded in  transmitting  rabies  in  this  manner. 

Genito-urinary  mucous  membrane. — Syphilis,  gonor- 
rhoea, in  man,  and  dourine  in  the  horse  are  generally 
inoculated  by  coition  in  the  absence  of  solutions  of 
continuity  either  of  the  vagina  or  urethra.  Fric- 
tions probably  aid  in  the  penetration  of  the  specific 
germs.  Absorption  by  these  intact  passages  can, 
therefore,  not  be  doubted. 

The  penetration  of  microbes,  therefore,  takes  place 


Pathogenic  3Iicrobes  in  the  Static  Condition.       59 

through  the  intact  mucous  membranes,  but  this  faculty 
may  give  rise  to  no  injurious  effects  upon  individuals 
who  are  in  absolutely  physiological  conditions.  M. 
Bouchard  has  given  the  following  explanation  of  the 
mechanism  by  which  the  normal  organism  opposes 
itself  to  the  penetration  of  the  germs  present  on  the 
natural  surfaces : — Germs  which  have  traversed  the 
epithelium  immediately  come  into  conflict  with  the 
white  corpuscles  distributed  in  the  derm  of  the  mu- 
cosa, and  by  these  they  are  taken  up  and  digested. 
If,  on  the  contrary,  the  economy  is  disturbed,  thrown 
out  of  equilibrium,  by  a  sufficient  cause  (repeated  in- 
-fluence  of  currents  of  cold  air,  influence  of  fear)  the 
enfeebled  white  corpuscles  allow  the  microbes  to 
break  through  the  barrier  which  they  are  charged 
with  defending.  The  experiments  of  Bouchard  were 
made  with  ordinary  germs;  their  results  are  applica- 
ble to  pathogenic  microbes,  with  this  difierence,  that 
it  is  necessary,  here,  to  take  into  account  a  supple- 
mentary factor  directly  related  to  the  pathogenic 
faculty :  we  refer  to  the  influence  that  the  secretions 
of  these  microbes  can  themselves  exert,  in  such  cases, 
upon  the  white  corpuscles,  in  attenuating  or  annihi- 
lating their  action. 

Wounds. — In  general,  wounds  are  the  surfaces  of 
predilection  for  the  absorption  of  pathogenic  germs 
not  only  on  account  of  the  division  of  the  tissues  and 
vessels  which,  in  a  manner,  opens  the  way  for  them, 
but  also  because  the  organism  is  not  prepared  with 
its  means  of  defense.  The  latter  has  to  be  organized 
upon  the  field,  and  but  too  frequently  proves  inade- 
quate to  repel  the  invaders.  ^Nevertheless,  hemor- 
rhage, and  the  phagocytic  action  of  the  elements  of 


60  31anual  of  Veterinary  Microbiology. 

the  tissues,  as  well  as  that  of  the  leucocytes  which 
speedily  accumulate  in  the  wound,  are  conditions  un- 
favorable to  absorption.  The  latter,  moreover,  de- 
pends upon  many  other  circumstances  bearing  upon 
the  nature  of  the  germ,  its  vehicle,  the  depth  and 
extent  of  the  wound,  etc.  The  microbes  of  tetanus 
and  those  of  gaseous  gangrene,  for  example,  only 
multiply  in  wounds  to  which  the  access  of  the  air  is 
limited;  their  activity  is  checked  by  atmospheric 
oxygen.  The  rapidity  of  penetration  is  influenced 
by  the  nature  of  the  medium ;  an  aqueous  medium 
will  be  more  readily  absorbed  than  a  solid  excipient 
or  one  of  thick,  colloid  consistence. 

Tuberculosis,  symptomatic  charbon,  and  grangren- 
ous  septicaemia  are  not  inoculable  by  sub-epidermic 
punctures,  whilst  this  inoculation  is  successfully  per- 
formed in  the  subcutaneous  cellular  tissue.  Absorp- 
tion is  always  more  easy  when  the  tissue  is  itself 
lacerated. 

Absorption  from  wounds  is,  in  general,  very  rapid ; 
glanders  has  been  seen  to  supervene  in  spite  of  deep 
cauterization  of  the  inoculated  wound  two  hours  after 
the  insertion  of  the  virus  ;  cauterization  after  a  lapse 
often  minutes  has  still  allowed  the  evolution  of  sheep- 
pox.  The  amputation  of  the  ear  of  a  rabbit  inocu- 
lated with  charbon  by  sub-epidermic  puncture  in  that 
region  has  not  prevented  the  irruption  of  the  disease, 
although  this  operation  followed  only  three  minutes 
after  the  inoculation. 

Infection  by  wounds  may  be  local  only,  or  it  may 
become  generalized;  in  the  latter  case  the  extension 
occurs  chiefly  by  the  lymphatics,  the  germs  then 
showing  tbeir  presence  in  these  vessels  by  the  lesions 


Physiology  of  Pathogenic  Microbes.  61 

which  they  determiue  in  the  corresponding  glands. 
But  pathogenic  germs  can  also  penetrate  directly 
into  the  blood-vessels  in  which  case  generalization 
occurs  much  more  rapidly. 


CHAPTER  II. 


PHYSIOLOGY    OF    PATHOGENIC   MICROBES. 

1.  Action  of  pathogenic  microbes  upon  the  organism.  Receptiv- 
ity. Immunity. — 2.  Reaction  of  the  organism  against  path- 
ogenic microbes.  Phagocytosis.  Bactericidal  condition. — 
3.  Evolution  of  the  bacterial  disease. 

I.  Action  of  microbes  upon  the  organism. 

MECHANISM    OF    THE    PATHOGENIC   ACTION. 

Pathogenic  germs  exert  their  action  upon  the 
economy  in  two  principal  ways,  of  themselves,  or  by 
their  secretion  products.  We  will  consider,  suc- 
cessively, the  mode  of  development  of  the  troubles 
which  they  occasion,  both  local  and  general. 

1.  Pathogeny  of  local  alterations. — In  local  lesions 
the  microbe  acts  at  first  like  a  foreign  body,  that  is, 
it  excites  a  purely  mechanical  irritation;  the  Koch 
bacillus  very  probably  acts  in  this  way  when  it  gives 
rise  to  tubercular  neoplasms ;  we  know,  indeed,  that 
the  injection  of  lycopodium  powder  into  the  blood 
develops  a  similar  lesion,  and  the  egg  of  the  strongy- 
liis  vasorum  appears  to  act  in  the  same  way  in  the 
pseudo-tubercles  which  it  occasions  in  the  dog. 


62  Manual  of  Veterinary  3Iicrohiology . 

This  mechanical  influence,  however,  seems  to  be 
much  the  least  important.  The  soluble  substances — 
diastases  and  ptomaines — secreted  by  the  microbes 
possess  very  active  properties  and  to  these  we  ascribe 
the  genesis  of  most  of  the  manifestations  of  the  in- 
fectious diseases. 

Microbic  diastases,  as  we  have  already  said,  repre- 
sent the  digestive  juices  of  the  microbes;  they  can 
therefore  act  chemically  upon  the  substance  of  the 
tissues,  provoking  hydrations  and  chemical  decom- 
positions, and  thus  lead  to  the  liquefaction,  softening, 
and  even  mortification  of  these  tissues.  These  dis- 
solutions are  sometimes  preceded  by  a  sort  of  coagu- 
lation (coagulation  necrosis). 

The  soluble  substances — diastases  and  ptomaines — 
may  possess  phlogogenic  properties;  in  this  case 
they  develop,  of  themselves  alone,  all  the  inflamma- 
tory phenomena  which  follow  the  inoculation  of  the 
microbes  from  which  they  come.  They  excite  swell- 
ing, proliferation,  and  fatty,  hyaline,  or  waxy  de- 
generation of  the  elements,  dilatation  of  the  vessels, 
exudation  of  products  more  or  less  plastic,  sometimes 
active  diapedesis  of  the  white  blood  corpuscles  and 
even  extravasations.  The  pneumobacillus  liquefaciens 
bovis,  isolated  by  Arloing  from  the  lesions  of  bovine 
contagious  pleuro-pneumonia,  secretes  a  diastase 
which  excites  inflammatory  cedemas  recalling  those 
of  the  disease  itself.  The  staphylococcus  pyogenes 
aureus  produces  a  diastase  and  a  ptomaine  which  are 
phlogogenic  and  pyogenic. 

The  local  alterations  which  supervene  in  conse- 
quence of  the  Introduction  of  certain  germs  into  the 
tissues  sometimes  depend,  at  least  in  part,  on  the 


Physiology  of  Pathogenic  Microbes.  63 

chemical  action  to  which  the  nutrition  of  these 
germs  gives  rise;  the  emphysematous  tumors  of 
symptomatic  charbon  and  of  traumatic  gangrene  are 
caused  by  the  abnormal  production  of  gas  which 
accompanies  the  fermentations  provoked  by  the 
anaerobic  microbes  of  these  diseases. 

2.  Pathogeny  of  remote  and  general  manifestations. — 
Anatomical  alterations  remote  from  the  original  point 
of  infection  may  be  produced  as  a  consequence  of  the 
penetration  of  the  pathogenic  microbes  into  the  lym- 
phatics and  blood-vessels;  their  pathogeny  is  identi- 
cal with  that  of  the  local  manifestations. 

The  arrest  of  the  microbes  in  vessels  of  small  cali- 
ber may  become  the  starting  point  of  secondary  me- 
chanical lesions;  we  refer  to  microbic  embolisms, 
comparatively  frequent  in  general  infectious  diseases, 
and  which  are  followed  by  infarcts,  stases,  etc.  But 
it  may  happen  that  the  secretion-products  alone  pene- 
trate into  the  circulation,  the  bacteria  remaining  in- 
trenched at  the  primary  focus ;  we  may  also  have 
localized  alterations  dependent  upon  special  proper- 
ties, dissolving,  phlogogenic,  or  pyogenic,  of  these 
products. 

Besides  the  functional  troubles  resulting  directly 
from  the  anatomical  lesions,  primary  or  secondary, 
seated  in  the  various  organs,  we  have  to  consider 
the  genesis  of  the  general  manifestations  which  ac- 
company microbic  diseases,  either  local  or  general. 

Fever  is  one  of  the  most  frequent  symptoms  ;  a 
certain  number  of  soluble  microbic  substances  excite 
hyperthermia.  This  almost  always  results  from  a  gen- 
eral nutritive  excitation  of  the  tissue  elements,  from 
contact  with  these  substances  ;  but  it  may  also  be  the 


64  Manual  of  Veterinary  Microbiology. 

result  of  a  diminution  in  the  loss  of  heat  through 
constriction  of  the  peripheral  capillaries.  Rise  of 
temperature  therefore  does  not,  in  all  cases,  imply 
increased  production  of  heat. 

Several  microbic  substances  are  known  to  possess 
this  pyretogenic  or  fever-begetting  property  :  those 
derived  from  the  bacillus  of  blue  pus,  from  Freid- 
lander's  microbe,  etc. 

Further,  the  soluble  products  of  the  anatomical 
elements  themselves  produce  similar  effects.  Ac- 
cording to  Gangolphe  and  Courmont,  necrobiosis  of 
the  tissues  develops  pyretogenic  substances  inde- 
pendent of  all  microbic  intervention.  These  authors 
have  observed  that  histournage  is  followed  by  fever 
when  the  testicular  products  are  able  to  penetrate 
into  the  blood,  whilst  fever  is  absent  if  the  precaution 
be  taken  to  put  a  ligature  completely  around  the  scro- 
tum so  as  to  prevent  all  absorption.  It  is  not  impos- 
sible that  the  super-activity  of  the  phagocytes,  strug- 
gling against  microbic  invasion,  becomes  also  the 
starting  point  of  the  production  of  pyretogenetic 
substances,  a  hypothesis  which  certain  facts  seem  to 
indicate.  We  know,  moreover,  that  extracts  of  flesh 
and  of  the  spleen  possess  similar  properties,  which 
thus  appear  to  belong  to  a  certain  number  of  the 
residues  of  normal  disassimilation. 

Some  soluble  substances  of  microbic  origin  excite 
the  phenomenon  of  hypothermia,  lowering  the  tem- 
perature of  the  body ;  this  property  is  possessed  by 
the  soluble  products  of  the  comma  bacillus  of  cholera, 
the  septic  vibrio,  and  the  staphylococcus  aureus. 

The  nervous  system  is  especially  sensitive  to  the 
action  of  these  products  of  microbic  origin,  in  the 


Physiology  of  Pathogenic  Microbes.  65 

way  of  excitation  (hyperkinesia  developed  by  the 
toxines  of  tetanus),  or  of  depression  (coma,  somno- 
lence, in  fowl  cholera  and  charbon ;  paralysis  consecu- 
tive to  diphtheria  and  to  the  pyocyanic  disease).  The 
heart,  the  respiratory  centers,  and  the  vaso-motor  cen- 
ter may  also  feel  the  influence  of  these  substances, 
from  which  may  result  sometimes  an  increase,  some- 
times a  diminution,  of  the  functional  activity  of  these 
organs. 

RECEPTIVITY. 

Heceptivity,  or  aptitude  to  contract  infectious  dis- 
eases, varies  in  accordance  with  a  large  number  of 
circumstances,  and,  especially,  with  the  species  and 
the  mode  of  inoculation,  with  the  individual,  age, 
heredity,  causes  of  depression,  the  quantity  and  the 
quality  of  the  virus,  and  the  association  of  the  virus 
of  more  than  one  disease. 

1.  Influence  of  species  and  of  the  mode  of  inocula- 
tion.— The  susceptibility  of  a  given  animal  species 
to  a  disease,  when  experimentally  inoculated,  does 
not  necessarily  imply  the  liability  of  that  species  to 
contract  the  disease  spontaneously. 

Tubercu  losis  develops  spontaneously,  with  great  ease 
and  frequency,  in  man,  cattle,  and  birds ;  it  is  much 
rarer  in  the  horse,  the  pig,  and  the  dog  under  the 
same  conditions;  as  for  the  rabbit  and  the  guinea 
pig,  which  it  is  very  easy  to  inoculate  experimentally, 
they  do  not  contract  the  disease  except  by  inocula- 
tion. 

Symptomatic    charbon,    appearing    spontaneously 
only  in  bo  vines,  is  inoculable  to  the  sheep,  the  goat, 
and  the  guinea  pig,  but  not  to  other  animals. 
6 


66  Manual  of  Veterinary  Microbiology. 

Rabies,  a  spontaneous*  disease  of  the  dog,  is  inoc- 
ulable  to  all  species  of  martimals  and  to  birds,  intra- 
cranial inoculation  being  always  successful,  whilst 
hypodermic  inoculation  gives  only  variable  results. 

Bacteridian  charbon  develops  naturally  in  cattle, 
sheep,  and  horses,  experimentally  in  all  the  domesti- 
cated mammals. 

Influence  of  the  individual. — All  the  individuals  of 
any  species  susceptible  of  contracting  a  microbic 
disease  do  not  take  that  disease  when  they  are  ex- 
posed to  the  contagion ;  some  of  them  are  less  sus- 
ceptible than  others  and  a  few  may  even  be  absolutely 
refractory. 

Influence  of  age. — Strangles,  and  distemper  of  dogs 
are  diseases  of  youth;  symptomatic  charbon  only  ap- 
pears in  cattle  of  from  six  months  to  four  years  and 
is  with  difficulty  inoculated  to  the  young  calf ;  guinea 
pigs  are  the  more  susceptible  to  charbon  the  younger 
they  are.  Pigs  of  less  than  four  months  are  much 
less  susceptible  to  rouget  than  adults ;  hence,  only 
very  young  pigs  should  be  vaccinated  against  this 
disease. 

4.  Influence  of  heredity. — Certain  predispositions  are 
inherited;  for  example,  that  of  children  born  of  con- 
sumptive parents,  to  contract  tuberculosis. 

5.  Influence  of  depressive  causes. — All  conditions 
which  have  a  debilitating  effect  on  the  organism  fa- 
cilitate microbic  invasion.  Pasteur  has  shown  that 
lowering  the  temperature  of  fowls  inoculated  with 
charbon  is  followed  bv  the  evolution  of  the  disease  in 
these  animals  in  spite  of   their  natural  immunity. 

*  [Acquired  by  transmission  from  its  own  kind. — D.] 


Physiology  of  Pathogenic  Microbes.  67 

Bouchard  has  shown  that  gradual  cooling  of  the 
guinea  pig  allows  the  entry  into  the  blood  of  this 
animal  of  the  microbes  distributed  on  the  surface  of 
the  mucosa.  Nervous  disturbances  of  a  depressive 
character  act  in  the  same  way:  fear. 

The  administration  of  chloral,  curara,  or  alcohol  to 
the  frog  and  to  the  dog,  which  are  refractory  to  bacte- 
ridian  charbon,  endows  them  with  receptivity  for  this 
disease.  Antipyrine  and  chloral  diminish  the  resist- 
ance of  the  chicken  to  the  same  afiection. 

The  attenuated  and  inoflFensive  bacillus  of  symp- 
tomatic charbon  becomes  pathogenic  and  causes  the 
disease  when  it  is  conjoined  with  lactic  acid,  or  tri- 
methylamine,  or  when  injected  into  a  tissue  pre- 
viously contused.  The  same  substances,  as  well  as  a 
similar  traumatism,  also  favor  the  implantation  of 
the  tetanus  bacillus. 

The  influence  of  these  very  diverse  conditions 
must  be  ascribed  to  the  action  which  they  exert  upon 
the  phagocytes,  the  protective  function  of  which  they 
diminish,  by  rendering  them  less  capable  of  digesting 
the  microbic  invaders. 

6.  Influence  of  the  quality  and  quantity  of  the  virus. — 
Receptivity  naturally  varies  with  the  special  degree 
of  virulence  of  the  germs  that  the  organism  receives; 
a  germ  which  is  toxic  for  a  given  species  may  become 
an  efficacious  vaccine  when  its  virulence  has  been  en- 
feebled. 

As  to  the  quantity  of  the  virulent  substance,  it 
especially  requires  attention;  the  influence  of  the 
dose  can  not  be  questioned  ;  the  natural  immunity  of 
Algerian  sheep  against  charbon  is  overcome  by  inoc- 
ulation of  a  large  dose  of  the  charbon  bacillus.     In- 


68  Manual  of  Veterinary  Microbiology. 

oculation  of  a  minimum  quantity  of  certain  germs 
confers  immunity,  whilst  a  larger  dose  produces  the 
fatal  disease  (gangrenous  septicjjemia,  symptomatic 
charbon). 

7.  Irijiuenee  of  microhic  associations. — The  suscepti- 
bility to  an  experimental  disease  is  increased  by  in- 
jecting, at  the  beginning  of  this  disease,  a  consider- 
able amount  of  the  soluble  products  coming  from  the 
microbe  inoculated  (Bouchard).  This  fact  has  been 
established  for  the  charbon  bacteridium,  fowl  cholera, 
the  staphyloccus  aureus,  bacillus  prodigiosus,  the  ba- 
cillus of  symptomatic  charljon,  the  pyocyanic  bacil- 
lus, etc.  This  is  the  more  striking  since  the  injection 
of  the  same  products  without  microbes  often  confers 
immunity.  Here,  on  the  other  hand,  it  aggravates 
the  trouble  or  renders  it  possible,  by  overcoming  the 
natural  or  acquired  immunity.  The  mode  of  action 
of  these  substances  consists,  in  this  case,  in  the  ob- 
struction which  they  oppose,  by  paralyzing  the  vaso- 
dilator nerves,  to  the  diapedesis  and  phagocytosis 
which  the  germs  of  the  disease  naturally  excite  when 
they  are  inoculated  to  vaccinated  subjects,  or  those 
which  are  naturally  refractory. 

The  adjuvant  action  that  the  microbic  secretions 
exert  in  association  with  the  microbe  from  which 
they  come,  may  also  be  manifested  in  association  with 
other  germs  ;  thus,  the  natural  immunity  of  the  rab- 
bit against  symptomatic  charbon  is  obliterated  if  we 
inject  to  this  animal,  at  the  same  time  with  the  char- 
bon bacteria,  a  sterilized  culture  of  the  staphylococcus 
aureus,  or  micrococcus  prodigiosus. 

The  same  interpretation  is  applicable  to  the  predis- 
posing  or  aggravating  influence  that  a  previous  or 


Physiology  of  Pathogenic  Microbes.  69 

concomitant  disease  exerts    upon  the   course   of  an- 
other infectious  disease. 

In  the  case  of  tetanus,  however,  the  association  of 
accessory  germs,  such  as  the  bacillus  prodigiosus, 
renders  more  certain  the  irruption  of  the  disease,  by 
provoking  diapedesis,  because  the  medium  then  be- 
comes more  favorable  to  the  multiplication  and  nu- 
trition of  the  tetanus  bacillus. 

On  the  other  hand,  the  presence  of  phlogogenic 
germs,  which  excite  an  excessive  diapedesis,  may  op- 
pose the  receptivity  for  a  given  microbe.  Thus,  re- 
covery from  malignant  pustule  nearly  always  occurs 
after  the  appearance  of  suppuration  ;  this  is  explained 
by  the  fact  that  the  white  corpuscles,  whose  accumu- 
lation is  brought  about  by  the  foreign  germs,  over- 
come the  bacteridium. 

Receptivity  of  the  tissues  and  organs. — Pathogenic 
germs  do  not  act  in  the  same  manner  upon  all  parts 
of  a  susceptible  organism;  they  appear  to  have  a  sort 
of  affinity  for  certain  organs,  for  certain  tissues. 
Thus,  the  bacillus  of  bacteridian  charbon  multiplies 
in  the  blood  whilst  that  of  symptomatic  charbon  only 
develops  in  the  connective  and  muscular  tissue  and 
is,  on  the  contrary,  killed  in  the  blood. 

The  pneumococcus  generally  limits  its  field  of 
operations  to  the  lung;  the  bacillus  of  pneumo- 
enteritis  to  the  lung  and  the  intestine;  that  of  glan- 
ders to  the  respiratory  apparatus  and  to  the  skin,  etc. 
This  elective  action  of  pathogenic  microbes  has,  in 
some  cases  only,  received  a  scientific  explanation. 

When  the  germs  have  penetrated  into  the  blood 
they  will  localize  themselves  preferably  in  the  organs 


70  llanual  of  Veterinary  Microbiology. 

predisposed,  enfeebled,  hence  less  effectively  prepared 
for  defense. 

IMMUNITY. 

Immunity  consists  in  the  absence  of  receptivity; 
it  may  be  natural  or  acquired.  Acquired  immunity  is 
most  frequently  consecutive  to  a  first  attack  of  the 
disease.  A  large  number  of  microbic  affections  do 
not  recur;  they  leave  behind  them  organic  changes, 
inappreciable  directly,  but  more  or  less  permanent, 
which  oppose  themselves  to  the  later  development  of 
their  germs  ;  the  individual,  once  recovered,  is  vacci- 
nated. This  is  the  case  in  variola,  vaccinia,  sheep 
pox,  syphilis,  charbon,  roiiget,  fowl  cholera,  pleuro- 
pneumonia, etc.  Other  diseases,  on  the  contrary,  can 
reappear  several  times  in  the  same  individual ;  such 
are  gonorrhoea,  simple  chancre,  diphtheria,  erysipelas, 
tuberculosis,  glanders,  etc.  In  the  case  of  these  two 
last  diseases  we  see,  in  reality,  specific  lesions  super- 
vene at  periods  very  remote  from  the  time  of  the  first 
appearance  of  the  affection,  which  would  not  happen 
if  one  or  more  first  attacks  of  the  disease  had  vacci- 
nated the  organism.  Immunity  may  also  be  com- 
municated by  artificial  means,  and  the  process  by 
which  this  is  effected  is  known  as  vaccination. 

The  duration  of  acquired  immunity  varies  greatly 
according  to  the  disease  and  the  individual  concerned. 
In  general,  immunity  consecutive  to  the  natural  dis- 
ease is  more  permanent  than  that  conferred  by  vacci- 
nation. 

Patient  researches  have  thrown  a  little  light  upon 
the  nature  of  immunity,  and  shown  that  it  operates, 
at  least  in  part,  through  the  active  intervention  of 
the  organism  which  possesses  it. 


Physiology  of  Pathogenic  Microbes.  71 

It  was  at  first  supposed  that  the  non-recurreuce  of 
infectious  diseases  was  due  to  the  fact  that  the  mi- 
crobes, at  the  time  of  the  first  attack,  had  abstracted 
from  the  blood  principles  indispensable  to  their 
growth,  or,  on  the  other  hand,  contaminated  the 
blood  with  principles  which  opposed  their  growth. 
In  short,  two  theories  were  entertained :  that  of  ex- 
haustion and  that  of  impregnation. 

The  first  is  to-day  abandoned  ;  immunity  has,  in 
fact,  been  overcome  by  employing  large  doses  of 
virus,  which  would  be  impossible  if  the  organism 
was  really  impoverished  in  substances  indispensable 
to  the  microbes. 

The  doctrine  of  impregnation,  on  the  other  hand,  is 
strongly  supported  by  the  discovery  of  vaccinating 
substances.  A  certain  number  of  microbes  secrete  sub- 
stances which  mix  with  the  fluids  of  the  tissues,  dif- 
fuse through  all  the  economy,  and  impair  the  vitality 
even  of  the  germs  which  have  produced  them ;  these 
preventive  substances  which  appear  not  to  be  identical 
with  the  toxic  secretions  of  microbes  oppose  them- 
selves to  a  recurrence  of  the  disease. 

The  existence  of  soluble  vaccinating  substances  has 
been  unquestionably  established  for  a  certain  number 
of  diseases  :  the  blue  pus  disease,  bacteridian  charbon, 
symptomatic  charbon,  cholera,  Pasteur's  septicaemia, 
pneumo-enteritis  of  the  pig,  etc. 

Impregnation  of  the  blood  does  not  account  for  the 
persistence  of  immunity.  Substances  prejudicial  to  the 
growth  of  the  germs  must  gradually  become  elimi- 
nated from  the  economy,  and  if  vaccination  were  due 
solely  to  their  presence,  its  effects  would  be  extin- 
guished in  a  comparatively  short  time. 


72  Manual  of  Veterinary  Microbiology. 

The  doctrine  of  the  impregnation  of  the  humors  is 
happily  supplemented  by  that  of  the  modification 
of  the  solid  parts  of  the  organism,  the  anatomical 
elements. 

In  acquired  immunity,  whether  it  be  consecutive  to 
a  first  attack  of  the  disease  or  be  conferred  by  vac- 
cination, the  fluids  and  tissues  possess  bactericidal 
properties.  Thus,  the  serum  of  the  rabbit  vaccinated 
against  the  pyocyanic  disease,  is  bactericidal  for  the 
microbe  of  this  disease;  but  this  property  also  be- 
longs to  the  solid  tissues  of  the  vaccinated  animals,  a 
fact  which  has  been  further  demonstrated  by  the  fail- 
ure of  attempts  to  cultivate  the  bacillus  of  symptom- 
atic charbon  in  the  thigh  of  a  guinea  pig  vaccinated 
against  this  aflectiou.  The  production  of  the  bacteri- 
cidal state  by  vaccination  is  established  for  a  certain 
number  of  germs :  the  bacillus  of  bacteridian  char- 
bon, symptomatic  charbon,  blue  pus,  the  vibrio  of 
cholera,  and  Metschnikofi''s  vibrio. 

This  property  is  communicated  to  the  vaccinated 
animal  by  the  mingling  of  the  vaccinating  substances 
with  the  nutritive  liquids  of  the  economy ;  the  con- 
tact of  these  fluids  with  the  tissue  elements  brings 
about  a  permanent  nutritive  modification  of  the  lat- 
ter; this  modification,  throughout  all  the  time  of  the 
duration  of  the  immunity,  exerts  its  influence  upon  the 
fluids  of  the  body,  endowing  them  with  the  microbi- 
cidal faculty.  By  virtue  of  this  faculty  the  virulent 
germs  against  which  the  vaccination  has  been  directed, 
when  they  attempt  to  invade  the  organism,  find  them- 
selves opposed,  attenuated,  through  contact  with  the 
fluids,  their  secretion  products  which  tend  to  diminish 
diapedesis  are  less  abundantly  produced  and  the  phag- 


Physiology  of  Pathogenic  Microbes.  73 

ocytes,  as  a  result  of  the  reaction  whicli  naturally 
occurs  on  contact  with  foreign  bodies,  issue  from  the 
vessels  and  take  advantage  of  the  situation. 

The  bactericidal  state,  therefore,  enfeebles  the  viru- 
lent microbes,  which  are  then  overcome  and  removed 
by  the  phagocytes. 

Immunity  being  in  some  way  fixed  in  the  anatomi- 
cal elements,  one  can  understand  its  persistence  and 
the  possibility  of  its  hereditary  transmission.  In 
natural  immunity  or  the  refractory  condition  the 
bactericidal  proj^erty  docs  not  appear  to  have,  at 
least  in  certain  cases,  the  same  importance  as  in  ac- 
quired immunity.  Indeed,  the  blood  of  an  individual 
refractory  to  a  given  microbe  can  serve  perfectly  for 
the  artificial  culture  of  this  microbe.  iNTevertheless, 
too  much  importance  should  not  be  attached  to  this 
fact.  We  shall  see,  later,  that  the  blood  is  always 
more  or  less  bactericidal,  but  that  this  faculty  disap- 
pears shortly  after  its  removal  from  the  vessels.  The 
bactericidal  property  of  the  blood,  therefore,  depends, 
without  doubt,  upon  its  contact  with  the  living  tis- 
sues, hence  we  can  form  no  accurate  estimate  of  this 
condition  of  the  blood  contained  in  the  vessels  of  the 
organism  by  comparing  it  with  the  same  fluid  outside 
of  the  vessels. 

We  know,  again,  that  natural  immunity  results,  in 
the  case  of  certain  microbes,  on  account  of  the  tem- 
perature of  the  organism  being  either  too  high  or  too 
low;  it  may  also,  as  M.  Arloing  has  demonstrated, 
be  the  result  of  a  natural  insusceptibility  of  the  or- 
ganism to  the  action  of  the  amorphous  products  se- 
creted by  the  microbes. 


74  3Ianual  of  Veterinary  Microbiology. 

II.  Reaction  of  the  organism  against  microbes. 

"We  will  consider,  successively,  under  this  head  : 
phagocytosis,  the  bactericidal  property,  the  isolation 
and  elimination  of  pathogenic  microbes,  and  varia- 
tions of  virulence  produced  by  the  organism. 

When  non-pathogenic  germs,  or  germs  in  which 
the  virulence  is  extinguished,  are  introduced  into  the 
tissues  of  an  animal,  these  germs  are  more  or  less 
quickly  destroyed.  The  same  thing  occurs  when 
pathogenic  germs  in  full  virulence  are  introduced 
into  the  system  of  an  individual  destitute  of  recep- 
tivity for  the  germs.  On  the  other  hand,  if  the  viru- 
lent germs  are  brought  into  contact  with  an  organism 
endowed  with  receptivity  they  will  multiply  and  be- 
come the  starting  point  of  morbid  troubles. 

There  are,  therefore,  in  the  organism  of  certain  ani- 
mals, conditions  capable  of  bringing  about  the  de- 
struction of  microbes.  These  conditions  are  multiple 
and  their  nature  is  as  yet  incompletely  elucidated. 
"We  know,  however,  that  the  organism  defends  itself 
against  invasion  through  the  intermediation  of  its 
figured  elements  and  of  its  fluid  parts. 

1.  Phagocytosis. — The  name  'phagocytosis  is  given  to 
the  destructive  action  of  certain  cells  toward  mi- 
crobes, these  cells  being  known  as  phagocytes.  The 
white  corpuscles,  in  this  regard,  take  first  place  in 
whatever  part  of  the  body  we  find  them  :  blood,  con- 
nective tissue,  lymphoid  organs  (spleen,  lymph  glands, 
marrow  of  bones,  etc.) ;  then  come  the  fixed  cells  of 
the  connective  tissue,  the  endothelial  cells  of  the 
capillary  vessels,  the  cells  of  soft  epithelia,  muscular 
fibers,  etc. 


Physiology  of  Pathogenic  Microbes.  75 

The  disease  develops  when  the  phagocytes  do  not 
succeed  in  killing  the  introduced  germs ;  in  the  op- 
posite case  it  fails  to  develop. 

The  injection  of  virulent  germs  in  a  susceptible  in- 
dividual paralyzes  the  phagocytes ;  on  the  contrary, 
the  injection  of  attenuated  germs  is  followed  by  an 
accumulation  of  leucocytes  (diapedesis)  around  the 
place  where  the  germs  occur;  the  germs  are  then 
taken  into  the  substance  of  the  leucocytes  and  di- 
gested by  them.  The  same  thing  happens  when  we 
inject  virulent  germs  into  a  non-susceptible  subject. 

All  the  germs  seized  by  the  phagocytes  are  not  in- 
fallibly destroyed;  hence,  these  migratory  cells,  in 
certain  cases,  seem  to  be  a  means  of  transferring 
bacteria  from  one  part  of  the  organism  to  another. 

The  leucocytes  possess,  in  common  with  some  of 
the  lower  vegetables,  the  property  (called  chemotaxis) 
of  moving  themselves  toward  certain  chemical  sub- 
stances. Now,  experiments  have  shown  that  the 
sterilized  or  filtered  cultures  of  a  certain  number  of 
mjcrobes  attract  the  white  corpuscles,  whilst  cultures 
of  other  microbes  either  have  no  action  upon  white 
corpuscles  or  paralyze  their  movements. 

Some  germs  secrete  substances  which  paralyze  the 
vaso-dilator  nerves,  thus  opposing  a  direct  obstacle  to 
diapedesis  and  therefore  to  phagocytosis.  As  an  il- 
lustration of  this  nervous  action  we  find  that  the  ear 
of  the  rabbit  which  has  received  an  injection  of  the 
soluble  products  of  the  pyocyanic  bacillus,  for  ex- 
ample, does  not  become  inflamed  when  a  layer  of 
croton  oil  is  applied  to  it. 


70  Manual  of  Veterinary  Microbiology. 

Microbes  whose  secretions  attract  the  leucocytes  * 
will  be  more  easily  overcome  by  them,  and  will  be 
less  dangerous  for  the  economy. 

Microbes  which  repel  the  white  corpuscles,  finding 
themselves  in  good  conditions  as  to  nutrition  and 
surroundings,  will  break  down  the  barrier  which  the 
corpuscles  oppose  to  them.  But,  under  conditions 
unfavorable  to  their  development,  their  secretions 
diminish  and  the  phagocytes  regain  all  their  power. 

Some  agents,  such  as  chloral  and  chloroform,  are 
capable  of  suspending  the  chemotaxic  faculty  of  the 
phagocytes. 

Certain  influences — physical  and  moral  disturb- 
ances, fatigue,  nervous  perturbation,  cold,  which  often 
cause  the  irruption  of  an  infectious  disease  or  aggra- 
vate it — have  a  depressing  efiect  upon  the  vaso-dilator 
nervous  apparatus,  interfere  with  diapedesis,  with 
phagocytosis,  and  therefore  favor  the  implantation  or 
multiplication  of  the  germs  of  disease. 

2.  Bactericidal  or  microbicidal  property. — By  the  bac- 
tericidal property  is  meant  the  peculiar  quality  of  the 
humors  of  the  economy — blood,  aqueous  humor,  peri- 
cardial serosity,  etc. — which  impedes  or  prevents  the 
multiplication  of  pathogenic  bacteria  in  these  fluids. 
This  bactericidal  faculty  varies  greatly  according  to 
tlie  species,  the  individual,  and  the  germs  with  which 
we  have  to  do.  When  microbes  are  introduced  into 
the  blood,  a  certain  number  of  them  perish ;  those 

*  [According  to  Buchner,  the  attractive  action  (positive  chemo- 
taxis)  exerted  by  sterilized  cultures  of  certain  microbes  toward 
leucocytes  is  dependent  on  the  proteid  contents  of  the  bacterial 
cells,  rather  than  on  their  secretion  products.  Baumgarten's 
Jahresbericht,  1890.— D.]     . 


Physiology  of  Pathogenic  31icrobes.  77 

which  resist  are  then  capable  of  multiplying ;  hence, 
the  normal  microbicidal  property  of  the  blood  is  tem- 
porary, not  permanent.  Fresh  blood  kills  the  bacillus 
of  charbon,  but  constitutes  a  suitable  medium  for  its 
cultivation  eight  days  after  its  removal  from  the  ves- 
sels. It  seems  to  be  established  that,  when  we  inject 
these  bacilli  into  the  blood,  they  multiply  there  only 
after  having  previously  multiplied  in  one  or  more 
organs  in  which  they  have  been  arrested.  When 
only  a  small  number  of  microbes  have  been  intro- 
duced they  may  all  be  destroyed,  and  then  the  inocu- 
lation fails. 

I^on-pathogenic  microbes,  introduced  into  the 
blood,  disappear  from  this  fluid,  becoming  arrested 
in  the  fine  capillaries  of  the  liver,  spleen,  marrow  of 
bones,  and  kidneys,  in  which  situation  they  are 
quickly  destroyed. 

Pathogenic  microbes  have  a  similar  experience 
when  they  are  inoculated  in  small  doses  into  the  cir- 
culation ;  like  the  preceding,  they  are  consigned  to 
the  fine  capillaries  of  the  parenchymatous  organs 
and  there  sustain  the  conflict  with  the  phagocytic 
elements  (endothelial  cells,  white  corpuscles,  etc.) 
According  as  the  issue  of  this  conflict  proves  favor- 
able to  the  microbes  or  to  the  phagocytes  we  may 
expect  the  appearance  or  non-appearance  of  the  dis- 
ease. 

The  evolution  of  the  microbic  disease  is  accom- 
panied, when  the  disease  is  non-recurrent,  by  the  pro- 
duction of  the  bactericidal  property.  This  condition 
is  slowly  evolved  by  the  progressive  action  of  the 
soluble  microbic  products  upon  the  fluids  and  tissues. 
When  it  has  acquired  sufficient  intensity  it  may  lead 


78  Manual  of  Veterinary  Microbiology. 

to  the  limitation  of,  or  recovery  from,  the  disease,  by 
opposing  itself  to  the  multiplication,  and  interfering 
with  the  nutrition  of  the  introduced  germs ;  the 
phagocytes  then  assume  the  duty  of  freeing  the  or- 
ganism from  these  enfeebled  germs. 

Elimination  of  microbes. — The  infected  organism 
may  free  itself  from  microbes  by  the  local  reaction 
which  their  presence  excites.  The  germs  of  pus,  for 
example,  determine  around  them  the  diapedesis  of 
leucocytes  and  these  destroy  by  phagocytosis  a  large 
number  of  germs.  On  the  other  hand,  at  the  same 
time  that  the  accumulation  of  leucocytes  within  the 
meshes  of  the  vascular  network  presents  a  certain 
degree  of  obstruction  to  the  nutrition  of  the  mi- 
crobes, the  microbic  secretions  act  upon  the  leuco- 
cytes, either  by  virtue  of  their  dissolving  disastases  or 
of  their  toxic  products,  so  that  a  parallel  destruction 
ensues  of  white  corpuscles  and  of  microbes.  Whilst 
this  double  destruction  goes  on  at  the  center  of  the 
focus,  the  surviving  germs  continue  to  invade  the 
peripheral  tissues  until  there  is  formed  all  around  the 
invading  army  a  sufficient  barrier  of  phagocytes. 
We  then  see  the  limitation  of  the  abscess,  and,  occa- 
sionally, its  encystment  by  fibrous  organization  of 
the  limiting  tissues ;  but  more  frequently  the  exten- 
sion of  the  pyogenic  inflammation  gives  rise  to  soften- 
ing, perforation  of  the  integument,  and  the  elimina- 
tion of  the  pus  and  therefore  of  the  germs,  the  cause 
of  all  the  trouble. 

The  natural  elimination  of  pathogenic  microbes  can 
occur  in  all  cases  in  which  the  lesions  they  deter- 
mine are  situated  near  the  surface  of  the  skin  or 
mucous  membranes  communicating  directly  with  the 


Physiology  of  Pathogenic  Microbes.  79 

exterior ;  this  elimination  is  more  or  less  complete 
according  to  the  case. 

When  the  germs  aredeeply  situated  their  expulsion 
may  still  take  place  through  certain  glands — the  kid- 
neys, the  salivary  glands  (rabies),  the  liver  (symptom- 
atic charbon).  The  elimination  of  infectious  germs 
by  way  of  the  kidneys  has  been  observed  for  a  large 
number  of  diseases;  generally,  if  not  always,  it  is 
the  consequence  of  the  irritation  which  the  microbes 
or  their  products  exert  upon  the  organ.  Many  mi- 
crobic  diseases,  in  fact,  are  accompanied  by  nephritis. 
The  more  or  less  complete  desquamation  of  the 
secretory  epithelium,  and  the  vascular  troubles  which 
then  supervene  account  for  the  passage  of  the  mi- 
crobes. 

If  the  elimination  of  the  figured  agents  of  the  in- 
fectious diseases  demands  conditions  somewhat  com- 
plex, the  rejection  of  their  secretions  is  more  readily 
accomplished,  since  these  substances  are  dissolved  in 
the  liquid  media  of  the  economy.  Their  filtration 
takes  place  especially  through  the  kidneys;  their 
presence  in  the  urine  has  been  established;  but  they 
may  also  transude  from  the  various  other  natural 
emunctories. 

4.  3Iodijications  of  virulence — The  bactericidal  prop- 
erty of  the  humors  has  the  power  of  attenuating  the 
virulence  of  pathogenic  microbes.  Inversely,  the 
absence  of  this  property  may  occasion  an  increase 
of  this  virulence.  Thus,  the  virulence  of  a  given 
microbe  may  become  increased  or  diminished  by 
passing  through  a  series  of  individuals  of  the  same 
species :  rouget  of  the  pig  becomes  more  active  when 
it  is  made  to  pass  through  the  pigeon  or  the  rabbit; 


80  Manual  of  Veterinary  Microbiology. 

on  the  contrary,  the  organism  of  tlie  ape  attenuates 
the  virus  of  rabies. 

The  virulence,  modified  by  one  species,  may  be 
changed  in  the  same  or  opposite  direction  for  other 
species  :  rouget  which  has  become  more  virulent  in 
the  rabbit  is  less  virulent  for  the  pig;  whilst  the  pass- 
age of  the  same  germ  through  the  pigeon  augments 
its  pathogenic  power  not  only  for  the  pigeon  but  also 
for  the  pig. 

We  could  multiply  examples  of  the  influence  of 
the  natural  organic  media  upon  pathogenic  germs. 
The  virus  of  rabies  attenuated  in  the  ape  is  also  at- 
tenuated for  the  dog,  guinea  pig,  and  rabbit.  Inocu- 
lated in  series  to  one  of  these  species,  it  regains  the 
virulence  which  it  naturally  possesses  in  the  dog;  in 
the  guinea  pig  and  rabbit  it  may  even  surpass  this, 
and  in  the  latter  attain  a  maximum  of  activity  be 
yond  which  further  passages  no  more  modify  it. 

III.  Evolution  of  the  bacterial  disease. 

After  what  we  have  seen  of  the  reciprocal  action 
of  the  organism  and  pathogenic  microbes,  little  re- 
mains to  be  said  of  the  disease  itself. 

The  determining  cause  of  microbic  affections  re- 
sides always  in  the  implantation  of  the  specific  germ 
in  a  susceptible  individual ;  but  such  common  causes 
as  cold,  mental  emotions,  overwork,  etc.,  may  take 
an  important  part  in  their  etiology,  by  diminishing 
or  suspending  the  normal  phagocytic  action,  as  we 
have  already  seen. 

The  germs  once  introduced  and  having  resisted  the 
combined  influence  of  phagocytosis  and  the  bacteri- 
cidal property,  their  effects  do  not  immediately  become 


Physiology  of  Pathogenic  31icrobes.  81 

appreciable.  A  preparatory  period  then  ensues  dur- 
ing which  the  microbe  proliferates,  multiplying  its 
means  of  action  upon  the  economy.  This  period 
corresponds  to  the  incubation.  It  is  shorter  the  bet- 
ter the  organism  is  adapted  to  the  life  of  the  germ; 
its  duration  also  varies  with  the  nature  of  the  germ 
and  its  virulence,  with  the  abundance  of  the  virus, 
with  the  receptivity  of  the  subject,  the  place  of  inoc- 
ulation, etc.  In  some  diseases  the  duration  of  the 
incubatory  period  is  almost  constant;  in  others  it  is 
very  variable  (rabies). 

Certain  diseases  have  several  successive  incuba- 
tions, or,  rather,  latent  periods,  during  which  the  dis- 
ease germ  ceases  its  activity,  slumbers,  to  resume  at 
a  later  period  its  course  of  invasion  (tuberculosis, 
dourine,  syphilis).  The  organism  is  then  in  the  con- 
dition of  latent  microbism. 

The  period  of  incubation  is  completed  when  the 
first  manifestations  of  the  morbific  action  of  the  virus 
appear;  the  premonitary  symptoms  are  in  no  way 
characteristic ;  yet,  in  the  course  of  an  epizootic, 
there  are  certain  signs  by  which  we  can  recognize 
the  invasion  of  the  disease  in  an  individual  previously 
healthy.  Thus,  a  persistent  fever  in  one  of  the  cattle 
of  a  stable  where  pleuro-pneumonia  prevails,  would 
excite  a  suspicion  of  its  invasion  by  this  disease. 

The  early  obscure  symptoms  more  or  less  quickly 
give  place  to  troubles  more  and  more  serious,  which 
clearly  characterize  the  affection  with  which  we  have 
to  do,  and  express  the  influence  of  the  progressive 
action  of  the  microbe.  This  is  the  period  of  increase. 
We  will  not  enter  here  into  details  of  the  common 
symptoms  of  microbic  diseases,  an  outline  of  which 


82  Manual  of  Veterinary  Microbiology. 

has  been  incidentally  given  in  connection  with  the 
subject  of  their  pathogeny.  We  will  only  say  a  few 
words  on  the  specificity  of  pathogenic  microbes.  At 
an  early  period  in  bacteriological  research  investi- 
gators applied  themselves  to  the  discovery  of  a  spe- 
cial microbe  for  each  disease ;  it  was  believed  that 
every  germ  produced  always  the  same  efiects.  We 
now  know,  however,  that  the  same  microbe  may  give 
rise  to  very  diiferent  diseases :  the  microbe  of  fowl 
cholera  gives  a  true  septicaemia  in  the  rabbit,  a  cir- 
cumscribed abscess  in.the  guinea  pig;  the  streptococ- 
cus pyogenes  develops  sometimes  an  abscess,  some- 
times an  erysipelas,  sometimes  puerperal  fever.  Sim- 
ilarly, a  given  lesion  may  be  consecutive  to  the  inoc- 
ulation of  dilFerent  microbes :  the  particular  inflam- 
matory lesion  which  has  received  the  name  of  tuber- 
cle has  for.  its  usual  cause  the  tubercle  bacillus;  but 
other  agents  can  develop  identical  changes,  which 
have  been  designated  pseudo-tubercles  in  order  to  dis- 
tinguish them  from  those  in  which  the  said  bacillus 
exists  ;  among  the  number  of  these  agents  we  may 
mention  croton-oil,  lycopodium  spores,  the  demodex 
folliculorum,  strongylus  vasorum,  the  utricular  sarco- 
spermia  of  the  muscles  of  the  pig,  the  actinomyces, 
the  pseudo-tubercle  bacillus  of  Courmont,  etc.  Ty- 
phoid fever  of  the  horse  appears  to  develop  under  the 
influence  of  various  species  of  microbes,  acting  inde- 
pendently. 

Microbic  specificity  is,  therefore,  not  absolute;  it 
depends  upon  the  organism  in  which  the  parasite 
has  implanted  itself  and  on  the  external  conditions 
which  may  have  influenced  the  latter.  Attenuation 
of  a  microbe  suffices,  indeed,  to  change  its  effects. 


Physiology  of  Pathogenic  31icrobes.  83 

An  infectious  disease  may  be  local  or  general,  ac- 
cording as  the  germs  are  confined  to  the  place  of  in- 
oculation or  have  invaded  the  circulation.  In  the  lat- 
ter case  the  general  affection  may  have  been  pre- 
ceded by  circumscribed  local  lesions,  or  it  may 
have  been  generalized  from  the  first.  In  either  case, 
a  general  disease  can  determine  localized  lesions, 
specific  or  not :  nephritis,  hepatitis,  enteritis,  inflam- 
matory enlargements,  etc.  These  secondary  inflam- 
mations of  the  secretory  organs  may  be  the  starting 
point  of  grave  complications  (auto- intoxications) :  ab- 
sorption of  bile,  urinary  intoxication.  Changes  of 
these  organs  present,  in  addition,  direct  obstacles 
to  the  elimination  of  the  soluble  microbic  products. 

The  multiplication  of  disease  germs  arrives,  at  the 
end  of  a  certain  time,  at  its  apogee ;  the  disease  then 
reaches  its  height.  The  secretion-products  of  the 
microbes  become  harmful  to  the  microbes  themselves ; 
in  mingling  with  the  fluids  they  communicate  to 
them,  as  well  as  to  the  tissues,  the  faculty  of  check- 
ing microbic  proliferation,  the  microbicidal  faculty; 
in  a  word,  they  vaccinate  the  organism.  The  vac- 
cinating effect  is  slowly  produced  under  the  influence 
of  the  prolonged  contact  of  these  products.  Im- 
poverishment of  the  organic  media  in  principles  in- 
dispensable to  the  microbes,  febrile  elevation  of  tem- 
perature, can  also  act  prejudicially  upon  the  latter. 
From  this  ensemble  of  unfavorable  circumstances 
there  results  enfeeblement  of  the  germs,  and  the 
phagocytes  take  upon  themselves  the  task  of  destroy- 
ing them. 

The  disease  then  subsides  on  account  of  the  fact 
that  the  toxic  substances  of  microbic  origin  which 


84  Manual  of  Veterinary  Microhiology. 

become  eliminated  in  various  ways,  are  no  longer  re- 
placed by  fresh  additions.  Recovery  is  not  complete 
when  the  elimination  of  these  substances  is  ended. 
Besides  the  weakness  of  the  patient,  local  troubles 
more  or  less  important  may  persist,  recovery  from 
which  will  take  place  gradually  now  that  the  cause 
which  engendered  them  is  removed. 

But  the  disease,  having  attained  its  height,  may 
terminate  in  death,  the  manner  in  which  this  is 
brought  about  varying  in  different  cases. 

Microbic  diseases  maybe  acute  or  chronic,  epizootic,  en- 
zootic of  sporadic.  The  gravity  of  some,  at  least,  of 
these  diseases  is  subject  to  variations,  whilst  others  of 
them  are  almost  invariably  fatal ;  charbon  and  rabies 
for  example.  Indeed,  from  the  knowledge  which  we 
have  gained  in  regard  to  receptivity,  immunity,  and 
the  resistance  of  the  organism  we  should  expect  all 
degrees  of  intensity  in  such  diseases.  In  epizootics  of 
great  severity  it  is  observed  that  the  first  animals  at- 
tacked are  more  severely  affected  than  the  last,  and 
that  the  number  of  the  individuals  attacked,  consider- 
able at  the  beginning,  rapidly  diminishes  toward  the 
end  of  the  attack.  This  is  probably  due  to  the  fact 
that  the  virus  fixes  itself  upon  individual  animals  by 
reason  of  their  special  susceptibility.  The  least  refrac- 
tory will  be  first  attacked,  will  be  severely  affected, 
and  the  virus  will  rapidly  multiply,  thus  increasing 
the  chances  of  infection  for  all  those  which  are  sus- 
ceptible to  the  disease.  On  account  of  this  dissemi- 
nation of  the  virulent  germs  the  less  susceptible  will 
also  be  finally  stricken,  but,  by  reason  of  the  fact  that 
they  do  not  offer  a  very  favorable  field,  the  microbic 
pullulation  will  in  these  be  less  extensive,  the  disease 


Transformation y  etc.,  of  Pathogenic  Microbes.      85 

less  serious,  and  the  chances  of  infection  for  the  indi- 
viduals yet  exempt  and  which  are,  moreover,  the 
most  refractory,  will  rapidly  diminish. 

The  disease  may  be  continuous  (charbon),    remittent 
(tuberculosis),  or   intermittent   (malaria). 


CHAPTER  III. 


TRANSFORMATION  AND  DESTRUCTION  OP  PATHOGENIC  MI- 
CROBES IN  THEIR  RELATION  WITH  HYGIENE  AND 
THERAPEUTICS. 

1.  Morphological  and  physiological  variations  of  pathogenic  mi- 
crobes.— 2.  Attenuation. — 3.  Preventive  inoculations.  Vac- 
cinations.— 4.  Destruction  and  annihilation  of  pathogenic 
germs. 

1.  Morphological  and  'physiological  variations  of  patho- 
genic microbes. 

"We  have  already,  in  the  first  part  of  this  work,  re- 
ferred briefly  to  the  influence  of  the  media  upon  mi- 
crobes in  general.  This  influence  acquires  great 
importance  when  pathogenic  germs  are  in  question. 
The  latter  may  undergo  considerable  changes  under 
the  influence  of  external  conditions. 

Pathogenic  germs  undergo,  from  this  cause,  varia- 
tions of  form  and  of  function. 

Physical  variations  are  quite  common  :  the  microbe 
of  avian  cholera  shrinks  when  its  cultures  become 
old;    that   of   rouget,   cultivated    after   its    passage 


86  Manual  of  Veterinary  Microbiology. 

through  the  rabbit,  increases  in  volume;  the  bacillus 
of  the  pyocyanic  disease  presents  itself,  according 
to  the  media  in  which  it  is  cultivated,  as  a  bacillus, 
a  spirillum,  or  a  micrococcus;  the  bacillus  of  gan- 
grenous septicaemia  grows  in  the  form  of  short  rods 
in  the  connective  tissue,  in  long  filaments  in  the 
serous  membranes  and  blood.  The  bacteridium  of 
charbon,  cultivated  in  bouillon  containing  a  small 
quantity  of  bichromate  of  potassium,  loses  its  power 
of  forming  spores,  subsequent  generations  to  which 
it  gives  birth  being  also  asporogenous.  A  tempera- 
ture of  42°  to  43°  produces  the  same  efllect  upon  the 
bacteridium. 

The  functional  variations  are  of  more  importance ; 
the  pyocyanic  bacillus,  placed  under  certain  condi- 
tions, ceases  to  secrete  the  coloring  matter  which 
characterizes  it.  There  are,  however,  variations  of 
virulence  w^hich  more  especially  interest  us.  The 
virulence  of  pathogenic  germs  may  be  increased  or 
diminished,  then  brought  back  to  its  normal  intensity, 
by  conditions  which  vary  with  each  microbe ;  these 
conditions  will  be  considered  more  in  detail  in  the 
following  paragraph. 

The  virulence  of  a  microbe  may  become  enfeebled 
to  such  an  extent  as  to  completely  lose  its  pathogenic 
powers ;  it  then  becomes  saprogenic.  From  the  rec- 
ognition of  this  fact  to  the  admission  of  microbic 
transformation  there  is  only  a  step,  j^evertheless, 
up  to  the  present,  we  have  not  observed  the  forma- 
tion of  a  new  species  at  the  expense  of  another 
Bpecies.  From  a  practical  point  of  view,  however,  it 
must  be  admitted  that  certain  saprogenic  species  may 


Transformation.,  etc.,  of  Pathogenic  31icrobes.      87 

incidentally  become  pathogenic  and  determine  the 
development  of  morbid  troubles  in  man  or  animals. 

II.  Attenuation  of  pathogenic  microbes. 

The  diminution  of  virulence  of  pathogenic  microbes 
is  occasionally,  not  always,  connected  with  a  diminu- 
tion in  their  general  nutritive  activity  ;  it  may  occur 
under  quite  varied  conditions,  either  spontaneously 
or  from  certain  definite  influences  purposely  brought 
into  play  by  the  experimenter;  we  will  here  study 
the  different  means  by  which  attenuation  may  be  ob- 
tained. 

1.  Attenuation  by  the  normal  atmosphere. — "We  al- 
ready know  that  the  majority  of  the  atmospheric 
germs  are  dead.  It  is  logical  to  admit  that  the  loss 
of  their  vitality  did  not  take  place  abruptly,  but,  on 
the  contrary,  was  gradually  produced,  and  that  what 
virulence  they  may  originally  have  possessed  also  dis- 
appeared gradually.  In  short,  the  germs  of  the  air 
are  attenuated  before  being  destroyed.  The  atmos- 
pheric conditions  which  determine  these  changes  in 
microbic  life  are  far  from  being  simple :  oxygen, 
light,  the  electrical  condition,  desiccation,  probably 
all  act  in  concert. 

But  the  external  air,  of  itself  alone,  can  bring 
about  the  attenuation  of  pathogenic  germs.  Very 
active  cultures  may  lose  their  virulence  in  some  days, 
weeks,  or  occasionally  months. 

Cultures  of  fowl  cholera,  abandoned  to  the  air, 
gradually  diminish  in  virulence  so  as  to  completely 
lose  it  at  the  end  of  a  time  varying  from  six  weeks 
to  two  months,  occasionally  much  less.  By  re-sowing 
these  germs,  in  way  of  attenuation,  at  periods  more 


88  Manual  of  Veterinary  3Iicrobiology. 

and  raore  remote  from  tlie  establishment  of  the  cul- 
ture, we  obtain  generations  of.  progressively  decreas- 
ing virulence,  a  series  of  viruses  less  and  less  power- 
ful, the  special  activity  of  which  is  preserved  when 
we  exclude  tliem  from  contact  with  the  air  or  when 
we  rejuvenate  them  without  intermission  by  cultures 
made  at  very  short  intervals.  Attenuation  is  here, 
therefore,  hereditary  through  successive  generations. 
Those  of  most  feeble  virulence  constitute  vaccines 
against  more  virulent  cultures. 

Cultures  of  the  germ  of  rouget  undergo  changes 
similar  to  those  of  fowl  cholera. 

As  to  cultures  of  the  charbon  bacillus,  they  are 
infinitely  more  resisting  to  the  destructive  influence 
of  the  atmosphere.  This  is  because  they  contain 
spores,  and  when  we  wish  to  attenuate  them  in  con- 
tact with  the  air  it  is  necessary  to  begin  by  prevent- 
ing sporulation.  Pasteur  has  attained  this  end  by 
cultivating  charbon  at  a  temperature  of  42°  to  43°. 
At  this  temperature,  the  culture  exposed  to  contact 
with  the  air,  rapidly  loses  its  virulence  ;  it  ceases  to  be 
fatal  first  for  the  larger  animals,  then  for  small  adults, 
finally,  for  small  animals  only  a  few  days  old..  The 
bacteridium  itself  perishes  much  more  slowly.  Now, 
each  degree  of  virulence  can  be  perpetuated  by  cul- 
tivating at  42°  to  43°  the  difierent  varieties  obtained, 
each  of  these  varieties  transmitting  its  special  viru- 
lence to  its  descendants.  If  they  are  returned  to  37° 
they  form  spores  possessing  in  embryo  the  special 
pathogenic  activity  of  the  attenuated  bacilli  from 
which  they  originate,  and  susceptible  of  transmitting 
the  latter  to  new  generations  cultivated  at  37°. 

According  to  M.  Chauveau,the  attenuation  of  the 


Transformation,  etc.,  of  Pathogenic  Microbes.       89 

bacteridia  by  the  preceding  process  is  the  effect  of 
the  heat  and  not  of  the  oxygen,  as  was  advanced  by 
Pasteur. 

The  least  virulent  varieties  produce  a  mild  disease 
Avhich  leaves  behind  it  immunity  for  the  varieties  less 
attenuated,  and  we  thus  have  vaccines  of  different 
degrees  of  strength  which  we  can  bring  into  action 
in  succession. 

The  attenuated  virus  of  fowl  cholera  and  of  bac- 
teridian  charbon  can  be  restored  to  their  normal 
virulence  by  passing  them  through  the  organism, 
first,  of  young  individuals,  and  then  through  those 
of  individuals  of  gradually  increasing  age. 

2.  Attenuation  by  compressed  oxygen  or  air. — M. 
Chauveauhassucceededin  attenuating  the  bacteridium 
of  charbon  by  subjecting  it  to  contact  with  pure  oxy- 
gen at  a  pressure  of  two  and  a  half  atmospheres  dur- 
ing fifteen  days  and  over,  at  a  temperature  of  35°  to 
36°.  This  attenuation  is  transmitted  through  suc- 
cessive generations  of  the  bacteridia.  He  has,  in 
this  way  obtained  an  energetic  vaccine  which  con- 
fers immunity  against  charbon  without  giving  rise  to 
accidents  in  the  vaccinated,  the  vaccinating  property 
being  wholly  retained  whilst  the  virulence  becomes 
progressively  enfeebled  until  it  entirely  disappears. 

3.  Attenuation  by  heat. — Heat  is  a  powerful  means 
of  destruction  of  germs;  we  also  find  it  among  the 
number  of  attenuating  agents.  It  is  to  Toussaint 
that  the  honor  belongs  of  having  first  demonstrated 
this  property  of  heat  in  connection  witli  charbonous 
blood.  His  methods  were  improved,  and  Chauveau 
applied  himself  to  the  task  of  heating  small  quanti- 
8 


90  Manual  of  Veterinary  Microbiology. 

ties  of  charbonous  blood  in  such  a  manner  that  all  the 
bacilli  were  influenced  to  the  same  extent;  the  de- 
gree of  eufeeblement,  in  fact,  depends  on  the  temper- 
ature and  the  duration  of  the  heating.  Chauveau  has 
prepared  two  vaccines,  intended  to  be  inoculated  in 
succession :  the  first,  the  least  active,  is  obtained  by 
heating  defibrinated  blood  at  50°  during  fifteen  min- 
utes ;  the  second,  by  heating  the  same  liquid  at  the 
same  temperature  during  nine  to  ten  minutes.  This 
last  vaccine  inoculated  to  animals  which  have  not  re- 
ceived the  first  may  yet  cause  the  death  of  some  in- 
dividuals. 

To  obtain  a  uniform  result  with  charbonous  blood 
it  is  necessary  always  to  use  fresh  blood  in  which  the 
bacilli  are  free  from  spores.  These  latter  are  endowed 
with  a  much  greater  power  of  resistance  and  are  not 
attenuated  like  the  bacilli;  hence,  in  his  researches 
upon  the  attenuation  of  cultures,  M.  Chauveau  first 
cultivated  the  bacteridia  at  a  temperature  of  42°  to 
43°,  in  order  to  prevent  the  formation  of  spores.  The 
asporogenous  bacteridia  are  heated  to  47°  during  three 
consecutive  hours;  they  are  then  attenuated  to  the 
extent  that  they  no  longer  kill  adult  guinea  pigs. 
Brought  then  to  the  favorable  vegetating  tempera- 
ture of  37°  the  attenuated  bacteridia  form  spores ;  but 
these  are  liable  when  placed  under  suitable  conditions 
to  produce  virulent  bacilli  again. 

In  order  to  render  attenuation  transmissible  to  suc- 
cessive generations  of  bacteridia  M.  Chauveau  then 
brought  the  sporulated  cultures  to  temperatures 
neighboring  on  80°.  The  attenuation  then  became 
fixed  upon  the  spores  and  the  latter,  returned  into 
nutritive  bouillon  at  37°,  produces  bacilli  attenuated 


Transformation,  etc.,  of  Pathogenic  Microbes.      91 

like  themselves.  Of  two  vaccines  prepared  iu  tins 
way,  the  iirst  comes  from  heating  at  84°  during  one 
hour,  the  second  from  heating  at  82°  during  the  same 
time. 

The  natural  serositj  of  the  specific  lesions  of  symp- 
tomatic charbon  may  also  be  attenuated  to  different 
degrees  by  a  temperature  of  65°  to  70°,  maintained 
for  a  greater  or  less  period  of  time  (Arloing,  Corne- 
vin  and  Thomas).  However,  these  authors  work  in 
preference  with  serosity  dried  at  a  temperature  of  30° 
to  35° ;  the  dried  virus  is,  in  fact,  more  fixed  than  the 
fluid  serosity ;  it  can  be  preserved  indefinitely  with  its 
normal  virulence;  its  attenuation  requires  tempera- 
tures varying  between  60°  and  110°.  The  authors 
have  prepared  two  vaccines  from  it:  one  heated  at 
100°,  the  other  at  85°:  Kitt  has  recommended  a  sinsrle 
vaccine  heated  at  90°. 

4.  Attenuation  by  solar  light. — Light  is  a  powerful 
bactericidal  agent ;  by  the  careful  use  of  this  prop- 
erty M.  Arloing  has  succeeded  in  gradually  attenua- 
ting the  charbon  bacillus. 

"  Thus,  a  culture  exposed  to  the  rays  of  the  sun 
during  nineteen  hours  furnishes  a  virus  which  kills 
the  guinea  pig  in  the  dose  of  one  drop ;  exposed  dur- 
ing twenty  hours,  a  culture  only  kills  one  guinea  pig 
out  of  two ;  exposed  during  twenty-five  hours,  such 
a  culture  no  more  kills  guinea  pigs  but  vaccinates 
them,  the  vegetating  power  of  the  bacillus  being  also 
considerably  diminished." 

The  diminution  of  virulence  thus  obtained  is  tem- 
porary and  is  not  transmitted  to  later  generations  of 
the  bacilli. 

5.  Desiccation. — Desiccation  has  been  utilized  by  M. 


92  Manual  of  Veterinary  llicrobiology. 

Pasteur  in  attenuating  the  virus  of  rabies.  The  cords 
of  rabid  rabbits,  suspended  in  vessels  containing 
pieces  of  caustic  potash  and  maintained  at  a  tempera- 
ture of  20°,  lose  their  virulence  in  seven  days ;  the 
diminution  takes  place  progressively,  so  that,  by  fix- 
ing the  successive  degrees  of  virulence  by  inocula- 
tion to  the  rabbit,  we  can  obtain  virus  of  gradually 
increasing  intensity. 

Attenuation  is  here  the  result  of  several  factors : 
desiccation,  oxygen,  and  the  temperature.  The  in- 
fluence of  the  last  agent  is  itself  very  great  if  we 
can  judge  by  the  increased  rapidity  with  which  at- 
tenuation is  produced  when  the  temperature  is  even 
slightly  increased ;  the  virulence  is,  in  fact,  obliterated 
in  seven  days  at  20°,  in  five  days  at  23°,  and  in  24 
hours  at  35°. 

6.  Attenuaiion  by  antiseptics. — Chemical  substances 
which  are  toxic  for  bacteria  can  diminish  the  vitality 
of  the  latter  when  they  are  employed  in  selected  doses 
and  their  contact  maintained  during  definite  periods 
of  time. 

The  bacillus  of  symptomatic  charbon  is  attenuated 
to  the  point  of  becoming  a  vaccine  in  contact  with 
sublimate,  at  1  to  5000,  with  carbolated  glycerine, 
eucalyptol,  and  thymol.  Carbolic  acid,  at  1  to  800, 
allows  the  multiplication  of  the  charbon  bacteridium 
but  prevents  sporulation.  Continuation  of  the  con- 
tact with  this  solution  gradually  weakens  the  viru- 
lence. The  same  results  are  obtained,  but  much 
more  rapidly,  with  bichromate  of  potassium  in  the 
proportion  of  from  1  in  2000  to  1  in  5000. 

The  soluble  substances  secreted  by  germs  can  di- 
minish the  virulence  of  other  germs ;  thus  bouillon 


Transformation,  etc.,  of  Pathogenic  31icrobcs.       93 

containing  the  residues  of  a  culture  of  cholera  atten- 
uates the  charboii  bacillus. 

7.  Attenuation  by  passage  through  the  organism  of 
animals. — Pathogenic  germs  are  subjected,  by  the  or- 
ganisms upon  which  they  implant  themselves,  to  cer- 
tain influences  of  which  we  have  already  had  occa- 
sion to  speak;  we  have  noted  especially  the  modifi- 
cations which  may  supervene  in  the  virulence  of  these 
germs  either  in  the  way  of  increase  or  diminution. 

Instances  of  attenuation  being  produced  under 
these  conditions  are  quite  numerous. 

The  microbe  of  rouget  of  the  pig  becomes  well  ac- 
climated in  the  pigeon  and  the  rabbit,  and  in  these 
two  species  acquires  great  virulence ;  but,  whilst  the 
organism  of  the  pigeon  renders  it  more  active  for  the 
pig,  that  of  the  rabbit  diminishes  its  virulence  for 
this  animal.  This  attenuation  is  preserved  in  cul- 
tures then  made  in  ordinary  bouillon,  and  these  cul- 
tures can  be  employed  as  vaccine  for  the  pig. 

The  bacilli  of  bacteridian  charbon  and  of  symp- 
tomatic charbon  are  attenuated  by  their  passage 
within  the  lymphatic  sacs  of  the  frog. 

The  virus  of  rabies  is  attenuated  in  passing  through 
the  organism  of  the  ape  to  the  extent  of  becoming 
inoffensive  for  the  dog  and  of  vaccinating  it.  It  re- 
sults from  the  preceding  facts  that  the  morbigenic 
faculty  of  microbes  can  be  lessened  in  different  de- 
grees; in  certain  cases  this  diminution  only  exists  for 
those  bacteria  upon  which  the  conditions  determin- 
ing the  attenuation  have  acted,  and  the  attenuation 
is  temporary ;  in  others  the  modification  to  which  the 
microbes  have  been  subjected  is  more  profound,  more 


94  Manual  of  Veterinary  Microbiology. 

durable,   and  persists  in  later  generations    of  these 
microbes. 

The  methods  which  furnish  an  hereditary  attenu- 
ation permit  of  obtaining  more  easily  large  quantities 
of  attenuated  virus,  and  are  more  especially  utilized 
in  the  preparation  of  vaccines. 

III.  Preventive  inoculations.     Vaccinations. 

The  organism  may  be  made  refractory  to  a  bac- 
terial disease  by  diiferent  means  :  by  inoculating  the 
natural  virus,  the  attenuated  virus,  a  chemical  vaccine, 
or,  finally,  a  virus  difierent  from  that  against  which 
it  is  desired  to  fortify  the  organism. 

1.  Preventive  inoculation  of  iiaiural  virus. — It  has 
been  observed  that  a  certain  number  of  contagious 
diseases  leave  behind  them  in  the  subject,  after  re- 
covery, a  solid  immunity  against  these  same  diseases. 
On  the  other  hand,  certain  diseases  purposely  com- 
municated show  themselves  much  less  dangerous  than 
when  they  prevail  naturally.  The  recognition  of 
these  facts  has  given  origin  to  variolization,  clavel- 
ization,*  preventive  inoculation  against  pleuro-pneu- 
monia,  etc.  The  first,  for  more  than  a  century,  has 
been  replaced  by  vaccination ;  the  second  is  still 
recommended  in  our  times,  in  default  of  a  means  of 
prevention  more  practical,  if  not  more  efiicacious. 

In  this  case  the  only  object  is  to  produce  a  disease 
of  the  same  nature  as  the  spontaneous  disease,  but 
mild  in  character,  not  threatening  the  life  of  the  in- 
dividual, yet  endowing  it  with  immunity.  This  end 
is  obtained  by  diminishing  the  number  of  the  germs 

*  [Artificial  infection  of  flocks  with  ovine  variola. — D.] 


OF  THB 

TVT-RSITY 


Transformation,  etc.,  of  Pathogenic  Microbes.       95 

which  engender  the  disease;  the  organism  overcomes  a 
small  dose  of  a  certain  virus  when  it  would  be  over- 
come by  a  larger  dose  :  a  minimum  quantity  of  the 
virus  of  gangrenous  septicaemia  and  of  symptomatic 
charbon  vaccinates  against  these  diseases ;  a  larger 
quantity  produces  the  fatal  disease.  Dilution  of  the 
vaccine,  of  the  virus  of  sheep-pox,  lessens  its  effects. 
The  severity  of  a  disease  may,  again,  be  diminished 
by  introducing  the  virus  by  a  special  way  known  to 
mitigate  its  influence :  the  blood  (pleuro-pneumonia, 
symptomatic  charbon,  gangrenous  septicaemia,  rabies), 
the  cellular  tissue  of  the  tail  (pleuro-pneumonia). 

2.  Preveyitive  inoculation  of  attenuated  virus. — Atten- 
uated viruses  develop  a  mild  disease  which  confers  on 
the  animals  an  immunity  more  solid  the  less  the  de- 
gree of  attenuation;  in  general,  we  have  recourse  in 
practice  to  several  specimens  of  virus  of  different  de- 
grees of  intensity ;  we  begin  with  the  weakest  and 
end  with  the  strongest;  a  solid  immunity  may  thus 
be  communicated  by  virus  sometimes  yet  very  active 
but  against  the  action  of  which  the  less  virulent  va- 
rieties have  fortified  the  organism. 

Attenuated  viruses  which  are  able  to  prevent  the 
development  of  infectious  diseases  are  called  vaccine 
viruses  or  simply  vaccines. 

The  two  charbons,  rouget,  pneumo-enteritis  of  the 
pig,  chicken  cholera,  rabies,  etc.,  have  furnished  vac- 
cines the  employment  of  which  is  to-day  admitted 
into  general  practice. 

3.  Preventive  inoculation .  of  soluble  vaccinating  sub- 
stances.— We  have  seen  above,  in  connection  with  the 
subject  of  acquired  immunity,  that  the  latter  results 
from  the  impregnation  of  the  organism  with  the  solu- 


96  31anual  of  Veterinary  Microhiologyi. 

ble  products  produced  by  pathogenic  bacteria.  These 
vaccinating  substances  are  known  for  a  certain  num- 
ber of  diseases — the  pyocyanic  disease,  bacteridian 
charbon  and  symptomatic  charbon,  cholera,  Pasteur's 
septicaemia,  pneumo-enteritis  of  the  pig,  rabies,  hu- 
man tuberculosis  (Koch's  lymph  will  give  immunity 
to  guinea  pigs),  tuberculosis  of  birds  (Courmont  and 
Dor  have  vaccinated  the  rabbit  by  means  of  the  solu- 
ble products  of  cultures),  etc. 

These  substances,  also  called  chemical  vaccines, 
have  a  great  advantage  over  the  figured  elements; 
the  attenuated  virus  may  indeed,  in  exceptional  cases, 
regain  its  virulent  properties,  and  this  unknown  to 
the  experimenter;  it  then  produces  the  fatal  disease 
instead  of  the  immunity  which  was  expected  of  it. 
The  soluble  vaccinating  substances,  however,  are  not 
entirely  free  from  danger;  they  are  nearly  always 
extremely  violent  poisons,  and  the  quantities  em- 
ployed must  be  judiciously  regulated.  The  discovery 
of  these  substances  is  of  such  recent  date  that  in 
practice  we  have  Jiot  as  yet  reaped  the  benefits  from 
them  which  we  may  reasonably  expect. 

Attempts  at  the  prevention  and  cure  of  the  mi- 
crobic  diseases  by  organic  liquids  coming  from  species 
naturally  refractory  to  these  diseases  have  been  made 
in  recent  times;  here,  again,  the  action  concerned  is 
a  chemical  one.  The  blood  of  the  goat,  transfused 
to  the  rabbit  at  the  time  that  the  latter  is  inoculated 
with  tubercular  products,  will  prevent  the  evolution 
of  tuberculosis;  if  the  transfusion  is  made  after  the 
disease  has  already  commenced,  it  will  retard  it  and 
may  even  cause  its  retrogression. 

Injection  of  the  blood  serum  of  the  dog  (haemocyne) 


Transformation,  etc.,  of  Pathogenic  Microbes.      97 

vaccinates  the  rabbit  against  tuberculosis ;  this  pre-' 
servative  action  is  more  intense  with  the  serum  of  a 
tuberculized  dog  and  manifests  itself  even  when  the 
injection  is  made  seven  dajs  after  the  virulent  inocu- 
lation. 

We  must  mention  here,  in  connection  with  pre- 
ventives of  a  chemical  nature,  the  attempts  at  vac- 
cination against  rabies  with  the  essence  of  tansy, 
against  tetanus  with  strychnine,  and  against  tubercu- 
losis with  tannin. 

4.  Preventive  inoculation  ivith  the  virus  of  another 
disease. — Cow-pox  is  preservative  against  variola;  we 
place  the  example  in  this  paragraph  although,  ac- 
cording to  recent  researches,  it  should  have  its  place 
along  with  the  inoculations  of  attenuated  virus.  Re- 
cent experiments  of  M.  Eternod  have,  in  fact,  demon- 
strated the  identity  of  variola  with  vaccinia.  It 
should  be  said,  however,  that  these  results  have  been 
contested. 

The  attenuated  microbe  of  fowl  cholera  vaccinates 
^fowls  against  charbon  and  against   Davaine's  septi- 
caemia; guinea  pigs  vaccinated  against  symptomatic 
charbon  are  also  vaccinated  against  the  septic  vibrio, 
but  the  reverse  does  iiot  hold  good. 

IV.  Destruction  and  annihilation  of  pathogenic  germs. 

The  destruction  of  pathogenic  germs  is  a  very  im- 
portant point  to  consider.  The  hygienist  and  the 
physician  should  apply  themselves  to  the  suppression 
of  dangerous  germs  wherever  they  exist,  that  is, 
upon  the  patient  and  upon  the  objects  which  have 
been  contaminated  in  his  surroundings;  this  opera- 
9 


98  Manual  of  Veterinary  Microbiology. 

tion  is  known  as  disinfection.  lN"ature  comes  power- 
fully to  their  aid  in  this  work  of  purification  ;  but  it 
often  requires  to  be  seconded  by  artificial  means,  the 
application  of  which  generally  abridges  the  natural 
duration  of  pandemic  or  panzootic  diseases.  We 
have  therefore  to  separate  the  causes  which  bring 
about  the  destruction  of  pathogenic  germs  into 
natural  and  artificial. 

It  may  be  stated  as  a  fundamental  principle  that 
adult  bacteria  in  their  vegetative  form  are  more  rap- 
idly destroyed,  whatever  be  the  cause  of  destruction, 
than  the  spores  or  organs  of  fructification.  For  the 
vegetative  forms  the  action  of  destructive  agents  is 
more  or  less  rapid  according  to  the  case;  a  bacterium, 
taken  in  full  vegetation  in  a  suitable  medium,  will  be 
more  easily  killed  than  one  in  the  condition  of  latent 
life,  for  example,  in  a  state  of  desiccation,  which  is 
equivalent  to  saying  that  death  will  be  more  easily 
produced  as  life  is  more  intense,  more  complete. 
Something  of  the  same  kind  is  observed  in  higher 
beings,  the  liability  of  these  to  suffer  from  adverse 
conditions  being  greater  as  their  requirements  are 
the  more  exacting.  A  young  bacterium  recently  de- 
veloped from  a  spore  is  more  sensitive  than  an  adult 
bacterium  which  has  attained  its  complete  develop- 
ment. 

1.  Natural  disinfecting  agents. — These  are  light,  des- 
iccation, and  oxygen. 

Light. — Light  excites  oxidation  of  the  organic  sub- 
stances which  enter  into  the  constitution  of  germs, 
and,  as  a  consequence,  involves  the  death  of  the  lat- 
ter. Other  conditions  being  the  same,  solar  light 
acts  more  rapidly  upon  non-sporulated  germs  than 


Transformation,  etc.,  of  Pathogenic  Microbes.      99 

upon  spores,  upon  germs  contained  in  a  liquid  or 
moist  medium  than  upon  those  which  are  in  a  dry- 
medium. 

The  time  necessary  for  destruction  by  light  varies 
from  a  few  hours  to  some  weeks,  according  to  the 
case;  solar  light,  however,  is  a  sure  agent  and  one 
whose  beneficial  action  operates  in  a  continuous  man- 
ner; hence,  we  should  guard  against  voluntarily  de- 
priving ourselves  of  it;  abundance  of  light  in  inhab- 
ited places  is  one  of  the  most  rational  of  hygienic 
measures. 

Desiccation. — Insufiiciency  of  water  arrests  the  mul- 
tiplication of  microbes ;  the  latter  then  lose  their  vi- 
tality more  or  less  rapidly.  But  the  spores  resist 
much  longer  than  the  bacteria  themselves ;  we  know, 
indeed,  that  the  virus  of  symptomatic  charbon  is 
dried  in  order  to  preserve  it,  and  that  the  germs  of 
tuberculosis  are  preserved  active  for  a  long  time  in 
pulverulent  sputum. 

Oxygen. — The  germs  of  the  air  are  destroyed  more 
or  less  quickly  under  the  combined  influence  of  des- 
iccation, which  arrests  their  pullulation  and  impairs 
their  vitality,  of  oxygen,  which  oxidizes  them,  and 
of  the  solar  light,  which  excites  in  them  this  oxida- 
tion; the  oxidizing  action  of  oxygen,  without  doubt, 
extends  itself  to  the  bacteria  of  waters  and  of  the 
soil,  these  perishing  more  or  less  rapidly  by  reason  of 
the  conditions  unfavorable  to  their  multiplication 
which  they  meet  in  these  media. 

Other  natural  agents,  less  important,  may  intervene 
to  destroy  pathogenic  bacteria;  among  these  we  will 
notice  again  the  ordinary  saprogenic  germs  which, 
finding  themselves  in  the  same  media  as  the  patho- 


100  Manual  of  Veterinary  Microbiology. 

genie,  may  lead  directly  to  the  death  of  the  latter; 
we  have  already  explained  this  action. 

2.  Artificial  disinfecting  agents. — These  are  heat  and 
the  antiseptics. 

Heat. — Heat  is  a  powerful  means  of  disinfection. 
Although  germs  withstand  extremely  low  tempera- 
tures, they  are  very  sensitive  to  increase  of  temper- 
ature. Temperatures  too  low,  as  well  as  those  which 
are  too  high,  are  unfavorable  to  the  proliferation  of 
pathogenic  microbes ;  but  the  latter  are,  in  addition, 
rapidly  fatal.  JSTevertheless,  the  spores  are  infinitely 
more  resistant  than  the  adult  germs;  whilst  these 
last  are  killed  in  all  cases  between  50°  and  100°,  the 
spores,  on  the  contrary,  require  a  temperature  of 
110°  to  125°.  However,  we  can  with  certaintv  kill  all 
spores  in  a  given  infusion  by  bringing,  on  ditferent 
occasions,  and  at  intervals  of  one  day,  the  said  in- 
fusion to  a  temperature  fatal  for  the  adult  form,  and 
taking  the  precaution  between  the  periods  of  heat- 
ing to  place  the  whole  at  a  temperature  favorable 
for  vegetation.  The  spores  which  the  boiling  has 
not  been  able  to  attack  become  transformed  into 
adult  bacteria  which  the  heating  of  the  next  day  will 
destroy. 

Heat  acts  with  more  rapidity  upon  bacteria  in  the 
moist  condition  than  when  dried,  upon  those  of  water 
than  upon  those  of  the  air. 

Whether  we  have  to  do  with  adult  germs  or  spores, 
with  a  dry  medium  or  a  moist,  the  duration  of  the 
heating  is  of  great  importance  and  can  be  supple- 
mentary to  insufficiency  of  temperature. 

Antiseptics. — This  name  has  been  given  to  chemical 
substances  capable  of  destroying  pathogenic  germs  or 


Transformation,  etc.,  of  Pathogenic  Microbes.     101 

of  arresting  their  development.  The  number  of  the 
antiseptics  is  quite  considerable,  but  there  are  some 
which  stand  at  the  top  of  the  list  and  merit  more  es- 
pecially the  confidence  of  the  practitioner.  These  are, 
indeed,  violent  poisons  for  nearly  all  microbes,  whilst 
the  others,  less  energetic,  are  only  really  efficacious 
when  they  are  directed  against  microbes  the  vitality 
of  which  is  easily  destroyed.  ISTevertheless,  we  can 
not  establish  a  general  rule  upon  this  subject;  the 
antiseptic  action  depends  not  only  on  the  chemical 
agent  employed,  but  also  on  the  microbe  concerned; 
it  is  also  dependent  upon  the  duration  of  contact,  the 
nature  of  the  excipient,  etc.  The  alcoholic  solutions 
of  carbolic  acid,  for  example,  are  less  antiseptic  than 
aqueous  solutions  of  the  same  concentration  because 
the  former  have  a  smaller  power  of  penetration  than 
the  latter. 

Antiseptic  substances  act  either  by  rendering  the 
media  unsuitable  for  the  multiplication  of  the  mi- 
crobes, or  by  opposing  themselves  to  the  production 
of  the  diastases  indispensable  to  the  elaboration  of  their 
foods. 

We  believe  that  it  may  be  profitable  to  reproduce 
here  the  classification  of  the  antiseptics  proposed  by 
M.  Miquel.  The  antiseptic  substances  are  here  classi- 
fied according  to  the  dose  of  the  substances  necessary 
for  the  sterilization  of  a  litre  of  beef  bouillon  : 

1.  The  most  jjowerful  antiseptics  :        -01  to  0*1  gram. 
(Oxygenated  water,  corrosive  sublimate,  nitrate 

of  silver.) 

2.  Very  strong  antiseptics :  0*1  to     1  gram. 
(Iodine,  bromine,  sulphate  of  copper.) 


102  Manual  of  Veterinary  Microbiology. 

3.  Strong  antiseptics :  1  to    5  grams. 
(Bichromate  of  potassium,  chloroform,  chloride 

of  zinc,  carbolic  acid,  permanganate  of  potas- 
sium, alum,  tannin.) 

4.  Moderate  antiseptics  :  5  to  20  grams. 
(Arsenious    acid,   boric    acid,    chloral   hydrate, 

salicylate  of  sodium,  sulphate  of  iron.) 

5.  Weak  antiseptics :  20  to  100  grams. 
(Borate  of  sodium,  alcobol.) 

6.  Very  weak  antiseptics :  100  to  300  grams. 
(Arseniate   of  potassium,  iodide  of  potassium, 

sea  salt,  glycerin.) 


CHAPTER  IV. 


METHODS    OF    DETERMINATION    OF    PATHOGENIC     MICROBES. 

1.  Examination,  investigation,  and  staining  of  bacteria. — 2.  Cult- 
ure of  bacteria. — 3.  Experimental  inoculations. 

We  have  now,  in  order  to  finish  the  general  study 
of  pathogenic  germs,  to  review  the  different  methods 
of  determination  of  these  germs,  that  is,  the  means 
which  we  have  of  distinguishingthem  from  each  other, 
or  recognizing  them.  This  means  consists  in,  1st,  mi- 
croscopical examination  of  the  bacteria  either  directly 
or  after  coloring  them;  2d,  their  culture  in  artificial 
media;  and,  3d,  the  test  of  the  effects  which  they  de- 
termine in  animals. 

lu  practice,  and  for  certain   germs  which  are  well 


Methods  of  Determination  of  Pathogenic  Microbes.  103 

characterized,  the  first  of  these  means  is  often  suffi- 
cient; but  in  other  cases  the  germs  to  be  determined 
must  be  subjected  to  the  test  of  the  three   reactions 
which  we  have  just  mentioned.     Thus,  for  example, 
the  bacillus  of  human  tuberculosis  and  that  of  avian 
tuberculosis  possess  identical  physical  characters,  re- 
act in  the  same  way  to   coloring  matters,  and  give 
cultures  difficult  to  differentiate  ;  on  the  other  hand, 
they  have  different  effects  on  experimental  animals. 
In  default  of  this  last  test  we  might  have  concluded 
that  the  two  germs  were  identical  when  they  are 
really  quite  distinct  in  some  of  their  physiological 
properties. 

I.  Examination,  investigation,  and  staining  of  bacteria. 
The  first  examination  of  a  liquid,  from  a  bacterio- 
logical point  of  view,  should  always  be  made  without 
the  help  of  reagents;  we  thus  see  the  germs  in  their 
real  form  and  size.  Desiccation,  or  the  addition  of 
staining  solutions  often  change  the  morphological 
character  of  microbes.  It  is  in  fresh  preparations, 
also,  that  we  are  in  a  position  to  judge  of  the  mobil- 
ity or  immobility  of  the  beings  which  we  wish  to 
study. 

Microbes  being  naturally  colorless,  little  refringent, 
and  consequently  difficult  to  distinguish,  staining 
methods  have  been  adopted  in  order  to  bring  them 
into  relief  in  the  media  to  be  examined. 

For  this  purpose  we  have  recourse  to  the  colors  de- 
rived from  coal —  aniline  colors — which  have  an  in- 
tense staining  power.  Without  entering  further  into 
the  details  of  this  subject,  we  may  say  that,  with  the 
stains   employed,  we  often  associate  adjuvant  sub- 


104  Manual  of  Veterinary  Microbiology. 

stances  whicli  act  the  part  of  mordant,  that  is,  which 
increase  the  penetrating  power  of  the  coloring  sub- 
stance and  render  its  fixation  more  energetic;  such 
are,  for  example,  alum,  potash,  soda,  lithia,  carbonate 
of  ammonia,  aniline,  etc.,  all  of  which  we  will  find 
in  the  various  liquids  used  in  histology  and  micro- 
biology. 

Heat  is  calculated  to  expedite  the  staining  of  mi- 
crobes, as  well  as  of  organic  tissues  in  general;  we 
shall  see  that  this  property  has  been  taken  advantage 
of  in  order  to  obtain  rapid  staining  of  various  bacilli, 
and  especially  those  of  tuberculosis. 

Two  groups  of  aniline  colors  are  recognized.  In 
the  first  {basic  colors)  the  coloring  substance  is  asso- 
ciated with  a  colorless  acid.  In  the  second  {acid 
colors)  it  plays  the  part  of  acid  and  is  combined  with 
a  colorless  base. 

This  distinction  should  be  noted  because  the  colors 
of  the  first  class  have  a  special  afiinity  for  cell  nuclei 
and  for  bacteria,  whilst  those  of  the  second  give  dif- 
fuse staining,  that  is,  fix  themselves  indifferently  on 
all  parts  of  the  cells  and  on  the  intercellular  sub- 
stance. 

The  basic  colors  include  gentian  and  methyl  violet, 
methyl  green,  methylene  blue,  fuchsin,  bismark  brown^ 
vesuvin,  and  safranin. 

The  principal  acid  colors  are  eosin  and  Jluorescine. 

Single  and  double  staining. — In  any  preparation  con- 
taining microbes  we  can  give  to  all  the  elements,  mi- 
crobic  and  non-microbic,  the  same  coloration.  In  the 
case  of  certain  micro-organisms  we  ought,  indeed,  to 
limit  ourselves  to  this  method  of  staining,  such  as 
the  germs  of  fowl  cholera,  pneumo-enteritis  of  the 


Methods  of  Determination  of  Pathogenic  31icrobes.  105 

pig,  etc.  With  these  germs  we  can,  at  most,  only 
attenuate  the  color  of  the  tissue  elements  with  the 
aim  of  bringing  more  distinctly  into  view  the  deeper 
color  of  the  bacteria.  Such  is  the  principle  of  a  pro- 
cess of  single  staining  which  has  been  applied  with 
slight  variations  by  different  micro-biologists,  and 
which  will  be  further  referred  to  later. 

Patient  researches  have  placed  at  our  command 
another  method,  called  double  staining.  This  method 
furnishes  excellent  preparations  and  renders  great 
service  in  the  study  of  the  distribution  of  microbes  in 
the  tissues.  Double  coloration  is  obtained  by  differ- 
ent means,  of  which  the  choice  is  not  indifferent,  for 
the  same  microbe  does  not  take  the  stain  by  all  of 
these  processes.  The  manner  in  which  microbes  be- 
have toward  the  methods  of  double  staining  is  even 
utilized  for  characterizing  them. 

The  principle  of  double  staining  is  as  follows: 
1st,  the  whole  preparation  is  stained  uniformly;  2d, 
all  the  elements  other  than  bacteria  are  decolorized 
whilst  the  latter  retain,  on  the  contrary,  the  color 
which  was  originally  imparted  to  them ;  3d,  the 
parts  decolorized  by  the  preceding  operation  are 
stained  with  a  T3olor  which  stands  out  distinctly  from 
that  of  the  microbe.  Thus,  the  latter  being  violet, 
the  contrast  color  will  be  red  or  brown;  if,  on  the 
contrary,  the  microbes  are  stained  red,  the  back- 
ground of  the  preparation  should  be  stained  blue  or 
green. 

We  may  have  to  examine  liquids,  or  solid  tissues. 
In  this  last  case  it  is  sometimes  necessary  to  make  a 
previous  examination  of  the  organic  pulp  and  study 
it  later  in  thin  sections.     We  shall  therefore  consider. 


106  Manual  of  Veterinary  Microbiology. 

in  succession,  the  various  manipulations  to  which  the 
liquids,  pulp,  and  sections  of  organs  must  be  sub- 
jected. 

Liquids — Direct  examination. — A  drop  of  the  liquid 
is  deposited  upon  a  slide,  covered  with  a  cover  glass, 
and  at  the  margin  of  the  latter  is  placed  a  drop  of 
coloring  matter ;  penetration  gradually  takes  place,  a 
process  which  may  be  assisted  by  manipulation  of 
the  cover  glass.  We  may  also  add  a  trace  of  coloring 
matter  directly  to  the  drop  of  liquid  to  be  examined 
before  inclosing  it  under  the  cover  glass.  For  this 
purpose  aqueous  solutions  of  gentian  violet  or  methyl 
violet  are  generally  employed. 

Examination  after  desiccation. — The  preparation  just 
described  has  its  field  of  usefulness,  but  it  has  the  de- 
fect of  not  being  permanent,  and,  especially,  of  not 
permitting  of  double  staining.  To  attain  these  ends 
the  liquids  are  rapidly  dried  so  as  to  fix  the  elements 
w^hich  they  contain  and  cause  them  to  adhere  to  the 
glass.  In  this  process  a  drop  of  liquid  is  spread  on 
a  cover  glass  either  by  means  of  a  spatula  or  by 
pressing  the  drop  betw^een  two  cover  glasses  which 
are  glided  upon  each  other  and  then  separated.  The 
cover  glasses,  thus  coated,  are  held  over  the  flame  of 
a  spirit  lamp  or  placed  upon  a  hot  plate,  the  surface 
containing  the  liquid  to  be  examined  being  directed 
upward  so  as  not  to  be  attacked  by  the  flame.  The 
drying  is  suflicient  when  the  liquid  is  transformed 
into  an  opalescent  layer ;  tins  layer  then  intimately 
adheres  to  the  cover  glass,  which  can  be  then  trans- 
ported through  a  series  of  reagents  without  risk  of 
the  former  becoming  detached. 

The  quantity  of  liquid  employed  should   be  very 


Methods  of  Determination  of  Pathogenic  Microbes.   107 

small  in  order  that  the  dried  preparations  may  form 
a  very  thin  coating,  which,  after  staining,  will  not 
obstruct  the  passage  of  the  rays  of  light.  This 
recommendation  is  of  special  importance  in  the  case 
of  organic  fluids  containing  many  histological  ele- 
ments, such  as  pus,  for  example,  of  which  only  a  very 
small  particle  should  be  taken. 

Before  all  staining,  it  is  sometimes  necessary  to  re- 
move the  fatty  matters  from  the  dried  substance  by 
immersing  it  in  chloroform  or  a  mixture  of  equal 
parts  of  alcohol  and  ether;  this  practice  is  indispensa- 
ble in  operating  upon  milk. 

Preparations  of  dried  blood  are  also  much  im- 
proved by  this  treatment :  under  the  influence  of  the 
alcohol  and  ether  mixture  the  corpuscles  acquire  a 
stability  which  desiccation  can  not  confer  upon  them, 
and  they  then  present  very  distinct  forms  in  stained 
preparations,  in  which  their  relations  with  the  mi- 
crobes can  be  studied.  This  is  a  highly  commenda- 
ble practice  which  much  increases  the  precision  of 
researches  bearing  upon  the  blood.  It  should  be  fol- 
lowed by  a  second  drying. 

Organic  pulps. — These  are  obtained  by  scraping  the 
freshly  cut  surface  of  the  organ  suspected  of  contain- 
ing microbes ;  a  small  particle  is  spread  out  between 
two  cover  glasses  in  a  thin  layer,  in  the  manner  indi- 
cated above,  and  then  dried. 

Microscopic  sections. — Tissues  which  are  intended  to 
be  cut  for  the  study  of  the  distribution  of  the  mi- 
crobes which  may  be  present,  should,  first  of  all,  be 
well  fixed,  that  is,  their  elements  well  immobilized  as 
regards  their  form  and  relations,  and  thus  placed  be- 
yond the   reach  of  cadaveric  changes.     This  is  es- 


108  Manual  of  Veterinary  Microbiology. 

pecially  necessary  in  the  examination  of  those  tissues 
for  micro-organisms,  as  these  latter,  living  independ- 
ently, may  continue  to  multiply  after  the  death  of 
the  tissues,  and,  further,  in  organs  left  in  contact 
with  the  air  foreign  germs  generally  develop  which 
are  prejudicial  to  the  accuracy  of  such  researches. 
These  accidents  are  avoided  hy  immersing  the  tissues 
to  be  preserved  in  absolute  or,  at  least,  strong  alco- 
hol, the  precaution  having  been  taken,  in  order  to 
render  the  action  of  the  alcohol  more  rapid  and  more 
intimate,  to  cut  the  organs  into  small  cubes  of  half 
to  one  centimeter  on  the  side. 

Sectioning  is  performed  in  various  ways,  but  the 
technique  of  this  operation  can  not  be  described 
here ;  its  study  belongs  to  the  domain  of  histology. 
Moreover,  this  mode  of  research  does  not  appear  to 
be  within  reach  of  all  practitioners  on  account  of  the 
instruments  and  time  which  it  requires,  and,  in 
nearly  all  cases,  it  can  be  omitted  when  the  differen- 
tial diagnosis  of  infectious  diseases  is  the  only  object 

in  view. 

Mounting  of  preparations. 

Cover  glasses. — After  staining,  the  cover  glasses 
must  be  dehydrated  to  admit  of  their  being  mounted 
in  Canada  balsam.  This  end  is  attained  very  rapidly 
by  drying  them  afresh  over  the  flame  of  the  spirit 
lamp  or  upon  the  hot  plate,  after  having  previously 
drained  them  between  two  folds  of  filter  paper.  As 
soon  as  the  cover  glass  is  dried,  the  preparation  is 
cleared  by  depositing  successively  upon  the  coated 
surface  a  drop  of  cedar  oil,  clove  oil,  or  bergamot  oil, 
a  drop  of  xylol,  and,  finally,  a  drop  ot  Canada  bal- 
sam  dissolved   in    xylol.     The   cover   glass   is   then 


Methods  of  Deterinination  of  Pathogenic  Microbes.   109 

placed  upon  the  slide  in  such  a  manner  that  the  bal- 
sam distributes  itself  between  the  two  glasses. 

"We  can  omit  having  recourse  to  clearing  (clove  oil, 
cedar  oil,  etc.),  and,  after  drying,  pass  directly  to  the 
balsam;  but  it  is  incontestable  that,  if  this  practice 
increases  a  little  the  duration  of  the  work,  it  also 
gives  more  distinctness  to  the  preparation. 

Sections. — Stained  sections  must  also  be  dehydrated 
in  order  to  be  mounted  in  balsam.  For  this  purpose 
they  are  passed  successively  through  specimens  of 
alcohol  of  different  strength,  ending  with  absolute  al- 
cohol (70,  90,  100  per  cent).  They  are  then  cleared 
by  immersing  them  in  one  of  the  substances  men- 
tioned above  (cedar  oil,  bergamot  oil,  clove  oil),  then 
placed  in  xylol,  and,  finally,  on  a  drop  of  balsam 
which  has  previously  been  deposited  on  a  slide  and 
which  is  now  at  once  covered  by  the  cover  glass. 

These  diverse  operations  may  be  made  upon  the 
slide  itself,  the  stained  section  having  been  spread 
and  fixed  at  the  start  by  a  semi-desiccation.  This 
last  is  easily  accomplished  either  by  the  aid  of  filter 
paper  which  is  used  to  absorb  the  water  from  the 
section,  or  by  moderate  heating. 

Methods  of  single  staining. 

Hydro-alcoholic  solutions  of  aniline  colors. — These  are 
made  extemporaneously  by  adding  a  few  drops  of 
a  saturated  alcoholic  solution  of  the  dj^e  to  a  watch 
glass  of  distilled  water.  They  are  largely  used  for 
single  staining,  especially  for  cover  glasses.  This 
method  is  sulficient  for  a  rapid  examination,  when 
the  object  is  merely  to  determine  the  presence  or  ab- 
sence of  microbes  in  the  preparation. 


110  Manual  of  Veterinary  Microbiology. 

The  solutions  most  used  are  those  of  gentian  violet, 
methyl  violet,  fuclisin,  and  methylene  blue.  A  few- 
minutes  contact  is  sufficient :  five  for  cover  glasses, 
fifteen  for  sections,  a  little  longer  in  the  case  of 
methylene  blue. 

Lofflers  method. — Cover  glasses  are  stained  for  from 
five  to  ten  minutes  in  the  following  medium  : 

Solution  of  caustic  potash,  1  to  10,000,  3  cub.  cent. 

Saturated  alcoholic  solution  of  methyl- 
ene blue,        .         .         .         .         .        1     "        " 

All  the  elements  are  stained  deep  blue.  To  bring 
out  the  microbes,  the  stained  preparations  are  im- 
mersed in  w^ater  containing  a  small  quantity  of  acetic 
acid,  one  or  two  drops  to  a  watch  glass;  in  this  they 
remain  on  an  average  only  one  minute;  they  are  then 
washed  with  distilled  water  and  mounted.  The  mi- 
crobes appear  colored  a  deej)  blue,  the  tissue  ele- 
ments a  light  blue. 

Method  of  Malassez  and  Vignal. — Staining  is  here 
made  with  Malassez'  blue,  which  consists  of : 

Aniline  water,  ....         9  cub.  cent. 

Absolute  alcohol,         .         .         .         .     1     "       " 

Saturated  alcoholic  solution  of  methyl- 
ene blue, 1     u       « 

Sections  remain  therein  ten  minutes,  cover  glasses 
five  minutes ;  they  are  then  decolorized  in  the  follow- 
ing mixture : 

Absolute  alcohol,     .         .         .         .1  cub.  cent. 

2  per  cent  solution  of  sodium  carbonate,  2     "       " 

Methods  of  double  staining. 
Gram's  method. — Gram's  violet  contains: 
Aniline  water,        ....         10  cub.  cent. 


Methods  of  Determination  of  Pathogenic  Microbes.    Ill 

Absolute  alcohol,       ....       1  cub.  cent. 

Saturated  alcoholic  solution  of  gentian 
violet,  .         .         .         .         .  1     "       « 

Cover  glasses  remain  in  this  fluid  five  minutes,  sec- 
tions fifteen,  after  which  they  are  transferred  for  one 
to  two  minutes  into  Gram's  solution  of  iodine  in  iodide 
of  potassium  which  consists  of: 

Iodine,  ......         1  gram. 

Iodide  of  potassium,         .         .         .  2  grams. 

Distilled  water,  ....     300  grams. 

They  are  then  completely  decolorized  in  absolute 
alcohol,  and  the  ground-work  of  the  preparation 
stained  red  (eosin,  picro-carniine)  or  brown  (bismark 
brown,  etc.)  The  violet  remains  fixed  on  the  mi- 
crobes, but  in  the  tissue  elements  it  is  replaced  by 
the  red  or  brown. 

Weigert's  method. —  Weigert's  violet  consists  of: 

Saturated  aqueous  solution  of  methyl  violet 

6  B,         .         .         .         .         .         .     68  grams. 

Absolute  alcohol,        ....         11  grams. 

Aniline,  .         .         .         .         .         .     "  3  grams. 

Sections  are  stained  from  five  to  ten  minutes,  im- 
mersed for  one  to  two  minutes  in  Gram's  iodine 
solution,  passed  rapidly  through  absolute  alcohol  (a 
few  seconds)  in  order  to  remove  the  greater  part  of 
the  water,  and  decolorized  in  aniline  oil ;  they  are 
then  cleared  in  xylol  and  mounted  in  balsam.  Since 
by  this  method  contact  with  alcohol  is  avoided,  it  is 
necessary  to  stain  the  groundwork  of  the  preparation 
in  red  or  brown  before  staining  with  violet.  This 
inversion  may  also  be  employed  without  inconven- 
ience in  staining  by  the  Gram  method.  The  employ- 
ment  of   alcohol   in   dehydrating   may   be    entirely 


112  Manual  of  Veterinary  31icrobiology. 

avoided  in  another  way ;  to  this  end,  the  section,  after 
coming  from  the  iodine,  or  even  before  staining,  is 
spread  out,  moist,  upon  the  glass  and  fixed  there  in 
a  state  of  semi-desiccation  by  slightly  heating  it  or 
by  the  aid  of  tissue  paper.  On  the  section,  thus 
fixed,  are  then  deposited  in  succession  a  drop  of  the 
different  reagents,  the  excess  of  each  being  carefully 
removed  with  the  tissue  paper  before  replacing  it 
with  the  next. 

In  the  methods  of  Gram  and  Weigert  as  well  as  in 
the  method  by  Xiihne's  violet,  which  we  will  consider 
later,  the  iodine  solution  of  Gram  may  be  replaced  by 
the  following : 

Corrosive  sublimate,     ...  1  gram. 

Water,      .         .         .         .         .         .100  grams. 

Alcohol,  enough  to  dissolve. 

All  microbes  do  not  take  indifferently  the  colora- 
tions obtained  by  the  above  methods.  For  a  given 
germ  one  method  may  be  more  suitable  than  another ; 
the  manner  in  which  the  microbes  behave  toward  the 
different  methods  of  staining  is,  indeed,  utilized  in 
distinguishing  them.  But  it  is  often  desirable  first 
of  all  to  determine  whether  or  not  a  given  substance 
contains  any  germs.  We  attain  this  end  by  the  fol- 
lowing method  : 

Kilhne^s  method. — Kiihne  has  succeeded  in  stain- 
ing nearly  all  microbes  by  employing  two  processes 
in  succession,  one  with  methylene  blue,  and  the  other 
with  crystal  violet.  Some  microbes  are  colored  only 
by  the  blue  (typhoid  bacillus),  others  only  by  the 
violet  (bacillus  tuberculosis,  bacillus  of  leprosy) ; 
others,  again,  and  these  are  the  most  numerous,  take 
the  two  colors  indiflerently. 


Methods  of  Determination  of  Pathogenic  Microbes.  113 

This  method  is  therefore  useful  for  determining  the 
presence  of  microbes  in  any  tissue.  In  its  execution 
an  equal  number  of  sections  are  treiited  bj  both 
methods. 

1.  Method  by  Kilhne's  blue.  The  blue  of  Kilhne  is 
obtained  by  adding,  drop  by  drop,  to  a  one  per  cent 
solution  of  carbonate  of  ammonia,  a  saturated  aque- 
ous solution  of  methylene  blue  until  the  mixture  ac- 
quires a  deep  blue  color.  The  sections,  after  dehy- 
dration in  alcohol,  remain  ten  minutes  in  this  blue 
liquid,  are  then  rapidly  decolorized  (two  or  three  sec- 
onds) in  a  1  to  1000  aqueous  solution  of  hydrochloric 
acid,  then  passed  into  distilled  water  to  remove  all 
trace  of  the  acid.  They  are  afterward  mounted  with- 
out passing  through  alcohol,  which  would  remove 
too  much  of  the  stain.  For  this  end,  after  removal 
from  the  water,  they  are  spread  out  on  a  slide  and 
there  allowed  to  dry,  or  better,  the  desiccation  is  has- 
tened either  by  means  of  a  current  of  air  or  very 
slight  heating.  They  are  then  cleared  in  xylol  and 
mounted  in  balsam. 

2.  Method  by  crystal  violet. — Kilhne's  violet  is  obtained 
in  the  same  way  as  the  blue  solution  by  adding  sev- 
eral drops  of  a  saturated  aqueous  solution  of  crystal 
violet  to  a  one  per  cent  aqueous  solution  of  carbonate 
of  ammonia  until  a  deep  violet  color  is  produced. 
Sections,  after  dehydration  in  alcohol,  are  left  in  this 
solution  ten  minutes  (two  hours  for  the  bacillus  tuber- 
culosis), washed  in  distilled  water,  and  immersed  for 
two  to  three  minutes  in  Gram's  iodine  solution  ;  from 
this  they  are  transferred  into  a  saturated  alcoholic 
solution  of  fluorescine  until  decoloration  is  nearly 
complete.    The  remaining  coloring  matter  is  extracted 


114  Manual  of  Veterinary  31lcrobioIoj>j. 

in  absolute  alcohol,  the  sections  are  cleared  in  oil  of 
cloves,  passed  into  xylol,  and  finally  mounted  in  bal- 
sam. 

To  obtain  double  staining  by  the  violet  method  it 
suffices  to  color  the  sections  with  picro-carmiue  be- 
fore placing  them  in  the  violet  solution. 

Kiihne  has  modified  this  process  so  as  to  avoid  the 
employment  of  alcohol  and  oil  of  cloves.  The  sec- 
tions, after  dehydration  in  alcohol,  are  immersed  for 
ten  minutes  in  the  concentrated  aqueous  solution  of 
crystal  violet,  to  which  has  been  added  hydrochloric 
acid  (one  drop  to  fifty  grams  of  the  solution).  They 
are  washed  in  distilled  water,  treated  with  Gram's 
iodine  solution,  replaced  in  water,  then  passed  rapidly 
(a  few  seconds)  through  absolute  alcohol  and  into 
aniline  oil  in  which  they  are  decolorized.  The  ani- 
hne  is  removed  by  xylol,  and  the  sections  mounted  in 
balsam.  The  employment  of  alcohol  can  be  entirely 
avoided  by  transferring  the  sections  after  the  action 
of  the  iodine  on  to  the  slide  and  there  treating  them, 
after  dehydration,  with  aniline,  xylol,  and  balsam,  in 
succession. 

Method  of  Berlioz. — This  gives  a  rapid  double  color- 
ation. The  sections  are  left  for  a  quarter  of  an  hour 
in  a  mixture  of  equal  parts  of  the  two  following 
solutions : 

1.  Distilled  water,      ...         84  cub.  cent. 
Aniline  water,    ....       6         " 
Methyl  violet  6  B,  .         .         .2-5  grams. 
Absolute  alcohol,        .         .        .10  cub.  cent. 

2.  Distilled  water,      ...         95         " 

90  per  cent  alcohol,     .         .         .'5         "      • 
Coccbiine, 2-5  grams. 


Methods  of  Determination  of  Pathogenic  Microbes.  115 

They  are  then  passed  tlirough  the  Gram  iodiue 
solution,  or  a,  five  per  cent  solution  of  sodium  car- 
hoiiate,  through  water,  alcohol,  etc.  This  method  is 
well  adapted  for  the  staining  of  charbon  material. 

Method  of  staining  spores  in  bacilli. — To  stain  spores 
dried  on  the  cover  glass  they  are  immersed  for  a  few 
minutes  in  hot  Ehrlich's  solution  and  washed  in 
alcohol;  the  cover  glass  is  then  held  for  a  second 
in  methylene  blue,  washed  again  in  alcohol,  and 
mounted  in  balsam.  The  bacilli  are  blue,  the  spores 
are  red  when  they  have  attained  their  development, 
uncolored  whilst  they  are  in  way  of  formation. 

II.  Culture  of  germs. 

The  majority  of  pathogenic  germs  can  be  culti- 
vated in  appropriate  artificial  media  placed  under 
suitable  conditions  of  temperature.  Our  aim  not  be- 
ing to  publish  a  complete  treatise  on  the  technique  of 
bacteriology,  we  will  refer  the  reader  for  details  upon 
this  point  to  special  works  on  the  subject,  and  limit 
ourselves  to  the  general  principles  of  the  question. 

We  will  review,  in  succession,  the  methods  of  ster- 
ilization, the  composition  and  preparation  of  the  va- 
rious culture  media,  the  sowing  of  these  media  and 
establishing  them  at  a  suitable  temperature,  the  physi- 
cal and  chemical  characters  which  the  cultures  may 
present  and  the  preservation  of  these  cultures. 

Sterilization. 

The  objects  and  instruments  which  are  employed 
in  the  culture  of  microbes  must  be  previously  freed 
from  all  living  germs.  Sterilization  is  obtained  by 
different  means  :  heat,  filtration,  antiseptics. 


116  Manual  of  Veterinary  Microbiology. 

Seat. — As  we  already  know,  bacteria  and  their 
spores  are  killed  by  heat.  For  this  it  is  necessary 
that  the  objects  which  contain  the  germs  be  raised  to 
a  temperature  varying  according  to  the  case.  There 
are  several  processes. 

a)  Flaming. — Objects  which  can  support  the  ac- 
tion of  a  rather  high  temperature  are  brought  into 
the  flame  of  a  spirit  lamp  and  subjected,  in  all  their 
parts,  to  a  temperature  of  about  200°.  Flaming  is 
practiced  chiefly  for  glassware,  occasionally  for  metal- 
lic instruments:  spatulas,  platinum  wire. 

6)  Dry  air  ovens  at  150°  C. — The  objects  to  be  steril- 
ized are  kept  for  about  two  hours  at  a  temperature 
of  150°.  To  this  end  they  are  placed  in  appropriate 
ovens,  furnished  with  a  temperature  regulator  and 
arranged  in  such  a  manner  that  the  temperature, 
through  the_circulation  of  hot  air,  is  nearly  the  same 
in  all  parts  of  the  apparatus.  These  ovens  are  pro- 
tected from  too  free  radiation  by  walls  composed  of  a 
substance  which  is  a  bad  conductor  of  heat,  such  as 
asbestos.  Sterilization  by  this  process  is  practiced 
chiefly  on  glassware,  wadding  and  metallic  objects. 

c)  Koch's  steam  sterilizer. — This  is  a  generator  of 
steam,  of  cylindrical  form,  containing  water  which  is 
kept  in  ebullition  by  the  combustion  of  gas ;  it  is  sur- 
mounted by  a  dome  of  plate  tin  enveloped  in  felt  to 
prevent  cooling.  The  temperature  of  the  cylinder, 
charged  with  steam,  is  maintained  at  100°,  a  tempera- 
ture sLifiicient  for  the  destruction  of  germs  and  spores 
in  the  moist  state.  Objects  to  be  sterilized  must  be 
left  in  the  upper  part  of  the  apparatus  from  two  to 
three  hours.     The  steam  sterilizer  is  employed  chiefly 


Methods  of  Determination  of  Pathogenic  Microbes.    117 

for  the  sterilization  of  culture  media,  and  for  objects 
which  can  not  sustain  a  temperature  of  150°. 

d)  Papin's  steamer — The  Chamherland  autoclave. — 
Sterilization  of  objects  in  fluid  media  is  much  more 
rapid  and  certain  when  they  are  subjected  during  ten 
to  fifteen  minutes  to  a  temperature  of  120°.  To 
realize  these  conditions  the  objects  are  inclosed  in  a 
Papin  steamer,  which  admits  of  obtaining,  under 
pressure,  the  temperature  indicated. 

Chamherland  has  recently  devised  an  autoclave  or 
steamer  specially  adapted  for  sterilization.  It  is  now 
found  in  all  laboratories.  It  is  merely  a  Papin 
steamer  modified  for  this  particular  use. 

e)  Discontinuous  heating. — Some  media,  such  as 
blood  serum  and  milk,  can  not  endure  a  temperature 
of  100°  without  undergoing  considerable  modifica- 
tions. For  the  sterilization  of  these  substances  we 
have  recourse  to  the  method  of  Tyndal,  which  con- 
sists in  killing  the  germs  in  full  vegetation,  an  ope- 
ration which  only  requires  a  temperature  of  58°, 
maintained  during  two  hours.  For  blood  serum  the 
temperature  should  not  exceed  58°,  for  this  medium  be- 
comes coagulated  at  a  higher  temperature.  The  first 
heating  not  having  killed  the  spores,  the  substance  is 
then  brought  to  the  ordinary  room  temperature,  or 
better,  to  37°;  the  spores  then  quickly  vegetate  and 
the  bacteria  to  w^hich  they  give  birth  will  be  killed 
by  a  second  heating  on  the  following  day.  This  ope- 
ration, repeated  four  or  five  times,  ends  in  the  certain 
sterilization  of  the  liquid. 

The  apparatus  employed  in  this  method  of  steril- 
ization consists  of  water  baths  maintained  at  a  con- 
stant temperature  by  a  regulator. 


118  Manual  of  Veterinary  31icrobiology. 

Filtration. — Germs,  like  all  solid  particles,  can  not 
pass  through  porous  substances  in  which  the  pores 
are  very  fine.  Liquids  filtered  through  such  a  sub- 
stance are  therefore  sterilized.  Hence,  it  is  possible 
to  obtain  sterilization  by  filtering  through  plaster  of 
Paris,  amianth,  or  porcelain. 

Chamberland  has  constructed  a  filter  for  steriliza- 
tion based  upon  this  property.  It  consists  of  a  hol- 
low tube  of  porcelain,  closed  at  one  end;  this  tube  is 
immersed  in  the  liquid  to  be  sterilized  and  a  vacuum 
produced  in  its  interior  in  any  of  the  ordinary  ways; 
the  sterile  liquid  passes  into  the  interior  of  the  tube. 
The  latter,  of  course,  should  have  been  previously 
sterilized  and  be  free  from  fissures. 

Ayitiseptic  solutions. — Sterilization  of  instruments, 
anatomical  specimens,  the  hands,  etc.,  should  be  ob- 
tained by  means  of  acidulated  solutions  of  corrosive 
sublimate  at  2  to  1,000,  carbolic  acid  at  5  per  cent,  or 
creolin  at  2  per  cent.  To  obtain  sterilization,  the 
objects,  after  thorough  cleansing,  must  be  washed 
with  these  solutions. 

Culture  media. 

The  cultureof  germs  in  artificial  media  necessitates 
the  presence  in  these  media  of  all  the  principles  es- 
sential to  their  life,  as  well  as  the  absence  of  all 
noxious  products.  Each  germ  having  special  nutri- 
tive requirements  of  its  own,  the  ideal  would  be  to 
possess  media  especially  appropriate  for  the  diverse 
pathogenic  species.  A  perfect  culture  apparatus 
ought  to  admit  of  the  continual  addition  of  nutri- 
ment, with,  at  the  same  time,  the  elimination  of  the 
residual  products ;  but  this  ideal  is   far  from  being 


Methods  of  Determination  of  Pathogenic  Microbes.    119 

realized :  the  nutritive  media  are,  for  the  most  part, 
prepared  empirically,  starting  from  complex  animal 
or  vegetable  products,  and  not  only  are  we  unac- 
quainted with  the  qualitative  and  quantitative  com- 
position of  these  media,  but  we  are  also  ignorant  of 
the  special  nutritive  value  of  the  essential  principles 
they  contain.  Moreover,  our  culture  apparatus  are 
very  imperfect;  during  the  progress  of  the  culture 
the  nutritive  material  becomes  exhausted  and  charged 
with  the  products  of  nutrition,  products  which  are 
prejudicial  to  the  normal  life  of  the  germs.  From 
tliese  circumstances  it  results  that  artificial  cultures 
do  not  always  give  individuals  conforming  with 
those  which  are  sowed,  and  that  often,  in  the  case  of 
pathogenic  species,  they  furnish  degenerated  beings 
incapable  of  acting  upon  man  or  animals. 

Generally  speaking,  all  culture  media  ought  to 'con- 
tain, besides  the  necessary  nutritive  substances,  at 
least  sixty  per  cent  of  water,  they  should  be  neutral 
or  slightly  alkaline,  and  absolutely  sterile.  A  con- 
siderable number  of  media  are  in  use;  they  embrace 
organic  liquids  :  milk,  urine,  blood  serum  ;  various 
decoctions :  bouillons  of  meat,  hay,  fruits,  beer  wort, 
etc.  These  materials  are  used  alone  or  after  the  ad- 
dition of  supplementary  nutritive  substances  :  pep- 
tone, gelatin,  glycerin,  glucose,  phosphates,  etc. 

Without  entering  into  the  details  of  the  prepara- 
tion of  these  diverse  media  we  will  describe  those 
most  commonly  in  use. 


120  Manual  of  Veterinary  Microbiology. 

A.  Fluid  media. 
1.  Bouillons. 

Bouillons  are  the  media  most  commonly  used.* 
They  are  prepared  from  the  flesh  of  the  different  do- 
mesticated animals,  but  especially  from  that  of  the 
calf,  the  ox,  and  the  chicken. 

One  kilogram  of  lean  meat,  free  from  bone,  is 
finely  minced  and  allowed  to  macerate  for  twenty-four 
hours  in  two  liters  of  water,  in  a  cool  place.  The 
reddish  fluid  which  bathes  the  meat  is  expressed, 
brought  up  to  its  original  volume,  and  to  it  is  added 
one-half  per  cent  of  table  salt  and  a  trace  of  potas- 
sium phosphate,  occasionally,  also,  from  one  to  three 
per  cent  of  peptone,  glycerin,  and  glucose.  The 
liquid  is  then  cooked  for  an  hour  at  100°  in  the  Koch 
sterilizer,  by  which  means  a  certain  amount  of  its  al- 
bumen is  coagulated;  it  is  strained  through  linen  and 
then  neutralized  with  a  one  per  cent  solution  of 
caustic  potash,  or  a  five  per  cent  solution  of  sodium 
carbonate.  The  filtered  and  neutralized  bouillon  is 
subjected,  during  ten  minutes,  to  115°  in  the  auto- 
clave, then  again  filtered.  This  bouillon,  introduced 
into  a  conical  fiask  stopped  by  a  plug  of  wadding,  is 
finally  sterilized  by  a  last  heating  of  a  quarter  of  an 
hour  at  115°.  It  is  then  ready  to  be  introduced  into 
the  culture  vessels.  The  culture  vessels  most  com- 
monly employed  are  the  Pasteur  bulbs.  These  are 
small  vials  of  thin  glass,  flat  on  the  bottom,  and  with 

*  [Except  for  special  purposes,  or  where  a  Large  quantity  of  the 
culture  is  required,  solid  media  are  now  more  in  use  than  bouil- 
lons.—D.] 


Methods  of  Determination  of  Pathogenic  Microbes.  121 

a  very  short  neck,  which  is  surmounted  by  a  ground 
glass  hood  ;  the  latter  is  prolonged  by  a  narrow  tube 
which  is  closed  by  a  plug  of  wadding.  These  ves- 
sels may  be  replaced  by  conical  vials,  etc.,  but  the 
latter  have  the  great  inconvenience  of  allowing  a  too 
rapid  evaporation  of  the  liquid. 

In  filling  the  Pasteur  vessels,  which  must  previously 
have  been  sterilized,  we  employ  with  advantage  a 
Chamberland  pipette.  This  is  a  flat  bottomed  bulb 
with  a  long  narrow  tube  bent  to  45°  and  filled  at 
one  part  of  its  length  by  a  plug  of  wadding;  from 
the  side  of  this  bulb  projects  horizontally  a  long  slen- 
der tube  sealed  with  the  flame  at  its  free  extremity. 
The  pipette  having  been  sterilized,  the  lateral  tube 
is  flamed,  the  point  broken  off  in  the  sterile  bouillon 
and  the  latter  slowly  aspirated  into  the  pipette.  This 
done,  a  quantity  (half  to  one  centimeter  in  depth)  of 
the  bouillon  is  allowed  to  flow  into  the  Pasteur 
culture  vessels,  the  latter  being  held  in  the  horizontal 
position,  in  order  to  avoid  the  entrance  of  air  germs; 
this  operation  should  be  conducted  in  a  room  free  from 
currents  of  air.  The  bouillon  having  been  introduced 
into  the  culture  vessels,  it  is  advisable  to  test  if  these 
are  really  sterile  by  placing  them  during  two  or  three 
days  in  an  incubator  ;  those  in  which  the  bouillon  be- 
comes turbid  contain  bacteria  and  consequently  must 
be  rejected.* 

*  [Usually  the  culture  media,  both  fluid  and  solid,  are  filled  into 
ordinary  test-tubes,  closed  with  cotton  and  sterilized  in  the  steam 
sterilizer.  Evaporation  is  to  a  large  extent  prevented  by  accu- 
rately fitting  a  piece  of  tin-foil  over  the  mouth  of  the  tube. — D.] 


122  Manual  of  Veterinary  Jlicrobiology. 

2.  31ilk. 

Milk  may  be  collected  in  a  state  of  purity  in  ster- 
ilized tubes  by  introducing  a  sterile  canula  into  the 
teat  after  the  latter  has  been  well  disinfected.  This 
is  the  best  means  of  obtaining  milk  free  from  germs, 
but  it  is  one  which  is  not  generally  available,  and, 
most  frequently,  we  are  compelled  to  sterilize  this 
liquid. 

This  is  done  in  the  autoclave  at  115°.  The  milk, 
without  the  cream,  is  then  introduced  into  the  Pas- 
teur bulbs  and  subjected  to  the  test  of  the  incubator. 

3.  Urine. 

It  was  in  urine  that  Pasteur  first  cultivated  the 
bacteridium  of  charbon.  The  urine,  after  collection, 
is  rendered  alkaline,  filtered,  and  sterilized  exactly 
like  the  bouillon.  It  may  be  employed  alone  or  after 
the  addition  of  supplementary  nutritive  substances. 

B.  Solid  media. 
This  consists  of  fluid  media  gelatinized,  coagulated 
blood  serum,  potatoes,  etc. 

Gelatinized  bouillons. 

Gelatinizing  substances  are  added  to  bouillon,  sim- 
ple or  complex,  so  as  to  render  it  solid  and  trans- 
parent on  cooling.  The  substances  employed  are 
gelatin,  gelose,  Iceland  moss,  etc. 

Nutritive  gelatin. — To  the  bouillon  whilst  in  prepa- 
ration and  before  boiling  is  added  ten  per  cent  of 
gelatin.  The  fluid  is  passed  through  a  cloth,  neutral- 
ized, and  the  process  generally  conducted  as  described 


Methods  of  Determination  of  Pathogenic  3iicrohes.    123 

for  bouillon.  The  product  should  be  of  a  citron  color 
and  perfectly  transparent  after  filtration.  It  is  then 
introduced  into  test  tubes  plugged  with  wadding,  and 
sterilized.  These  tubes,  filled  to  one-third  of  their 
height,  are  then  placed  in  a  wire  cage  and  kept  in 
the  autoclave  at  105°,  during  ten  minutes.  The 
gelatin  solidifies  on  cooling  and  the  tubes  are  then 
ready  for  use. 

Gelose  or  agar-agar. — This  is  a  gelatinous  substance 
coming  from  certain  algse  of  the  Indian  Archipelago. 

It  is  added  to  the  bouillon  whilst  in  preparation,  in 
the  proportion  of  one  to  two  per  cent,  and  the  further 
process  conducted  as  has  already  been  described  for 
gelatin.  The  addition  of  the  agar  often  renders  the 
liquid  turbid,  and  this  tarbidi'ty  persists  in  spite  of 
filtration;  it  is  with  the  view  of  obviating  this  in- 
convenience that  it  has  been  recommended  to  inti- 
mately mix  with  the  mass,  after  cooling  to  50°,  the 
white  of  an  egg  beaten  up,  and  then  bring  the  whole 
to  ebullition  again.  In  coagulating,  the  albumen 
carries  with  it  all  the  substances  in  suspension  and 
the  product  becomes  clearer.  However  it  always  re- 
mains slightly  opalescent. 

The  filtration  of  this  liquid,  like  that  of  gelatinized 
liquids  in  general,  ought  to  be  performed  while  hot, 
and  it  requires  some  time.  A  hot  filtering  apparatus 
is  employed,  consisting  of  a  glass  funnel  contained  in 
a  larger  one  of  copper  and  separated  from  this  last 
by  a  space  full  of  water  kept  at  the  temperature  at 
which  the  gelatinous  mixture  becomes  fluid.  The 
filtration  thus  obtained  is  slow,  for  the  gelatin  dries 
and  hardens  upon  the  filter  where  it  contacts  the 
walls  of  the  glass  funnel. 


124  Manual  of  Veterinary  Microbiology. 

For  filtrations  of  this  kind  we  have  employed  with 
advantage  a  special  support  bearing  a  simple  glass 
funnel  provided  with  a  lid  and  adjusted  above  a  con- 
ical vessel.  The  gelatinous  mass  to  be  filtered  hav- 
ing been  introduced  into  the  funnel  upon  an  ordinary 
filter,  the  whole  is  placed  in  the  Koch  steam  sterilizer. 
We  thus  obtain  a  rapid  filtration  without  desiccation 
or  loss  of  the  fluid,  since  the  filtration  takes  place  in 
an  atmosphere  of  steam.  The  agar  and  gelatin  hav- 
ing been  poured  into  tubes  and  sterilized,  the  latter 
are  placed  in  the  cold,  some  in  vertical  position,  others 
inclined  so  as  to  distribute  the  mass  in  a  very  large 
oblique  layer;  either  the  surface  of  this  layer  or  the 
depth,  in  the  vertical  tubes,  serves  as  a  field  for  cul- 
ture. 

Agar  has  several  advantages  over  gelatin:  it  is  not 
fluidified  by  the  growth  of  germs,  it  remains  solid  at 
40°,  and,  therefore,  admits  of  cultures  in  the  incu- 
bator at  39°;  it  may  be  subjected  to  cooking  for  a 
long  time  without  losing. its  gelatinizing  power.  On 
the  other  hand,  it  has  the  disadvantage  of  being  al- 
ways slightly  cloudy,  is  not  well  adapted  for  plate 
cultures,  and  gives  cultures  which  are  not  well  de- 
fined. 

Agar-gelatin. — With  the  aim  of  making  plate  cul- 
tures at  the  temperature  of  39°,  Jensen  has  recom- 
mended, for  the  solidification  of  the  bouillon,  a  mix- 
ture of  agar  and  gelatin.  He  adds  to  the  bouillon  5 
per  cent  of  gelatin  and  0.75  per  cent  of  agar.  The 
preparation  is  very  clear,  it  is  liquefiable  at  a  tempera- 
ture which  does  not  kill  the  germs,  and  it  remains 
solid  at  39°. 


Methods  of  Determination  of  Pathogenic  Microbes.  125 

Gelatinized  serum. 

A  solid  medium  of  frequent  use  is  sterilized  and 
cooked  blood  serum.  Many  methods  are  employed 
in  collecting  and  sterilizing  the  serum  ;  these  we  re- 
frain from  describing  here  and  limit  ourselves  to  a 
description  of  that  which  we  are  accustomed  to  use. 
Blood  drawn  from  the  jugular  of  the  horse  or  the  ox 
is  collected  in  deep  cylindrical  glass  vessels  and  left 
in  the  cold  for  twenty-four  hours.  The  clot  contracts 
and  the  serum  comes  to  the  surface;  the  latter  is 
collected  by  means  of  a  pipette  and  introduced  into 
conical  vials  to  be  sterilized. 

Sterilization  is  obtained  by  conveying  the  serum 
on  several  successive  days  into  a  water  bath  a  58°, 
and,  each  day,  leaving  it  there  for  two  hours.  The 
bath  is  provided  with  a  thermo-regulator  by  which  a 
temperature  of  58°  is  quickly  obtained,  a  condition 
indispensable  to  prevent  the  germs  from  multiplying 
too  much  and,  in  consequence,  altering  the  coagula- 
bility of  the  serum.  After  eight  days  heating  the 
liquid  maybe  considered  sterile ;  it  is  then  distributed 
in  test  tubes  by  means  of  a  Chamberland  pipette. 
Other  nutritive  substances,  peptones,  glycerin,  etc., 
may  be  added  to  the  serum  before  sterilization. 

The  cooking  of  the  serum  takes  place  in  double 
walled  ovens  so  arranged  that  the  tubes  may  be  in- 
clined so  as  to  spread  out  the  liquid.  These  ovens 
are  regulated  to  70°;  the  tubes  are  removed  as  the 
serum  in  them  becomes  coagulated.  Before  being 
used  these  tubes  are  tested  during  three  days  in  the 
incubator. 


126  31anual  of  Veterinary  Microbiology. 

Potatoes. 

Some  germs  admit  of  cultivation  upon  the  potato. 
For  the  preparation  of  fliis  medium  sound  tubers 
with  smooth  skin  are  selected,  thoroughly  washed  in 
water  with  a  brush,  and  allowed  to  soak  some  time 
in  1  to  1,000  sublimate  solution.  They  are  then 
cooked  by  steam  at  100°,  or  in  the  Chamberland  auto- 
clave, cut  in  two  with  a  previously  flamed  table- 
knife,  and  deposited  in  a  moist  chamber. 

A  moist  chamber  is  usually  represented  by  two 
crystallizers  of  different  sizes,  and  well  disinfected ;  a 
piece  of  filter  paper  saturated  with  sublimate  solution 
is  placed  in  the  smaller,  which  is  then  covered  by  the 
larger.  We  thus  obtain  a  moist  space  protected  from 
the  atmospheric  germs. 

Sometimes  potatoes,  cut  in  sections,  are  cooked  in 

tubes   ready  for  culture ;   these  have  a  constriction 

near  the  base  to  retain  the  potato  about  the  middle 

of  the  tube. 

Methods  of  culture. 

In  order  to  cultivate  germs  we  must  first 'possess 
pure  sowings.  Occasionally  the  germ  may  be  ob- 
tained pure  from  the  organism  in  which  it  has  de- 
veloped, as,  for  example,  in  bacteridian  charbon, 
chicken  cholera,  rouget  of  the  pig,  etc. 

In  most  cases  the  micro-organisms  do  not  occur  in 
a  state  of  complete  purity  in  the  parts  of  the  organ- 
ism in  which  they  pullulate ;  it  then  becomes  neces- 
sary, first  of  all,  to  separate  them  from  other  germs. 
We  have,  therefore,  to  describe,  successively,  the 
methods  of  isolation  of  germs,  the  inoculation  of  the 


Methods  of  Determination  of  Pathogenic  3Iicrohes.  127 

various  media,  and  the  establishment  of  a  suitable 
temperature. 

Methods  of  isolation. 

The  isolation  of  mixed  germs  may  be  obtained  in 
several  different  ways.  One  method  of  isolation  is 
based  upon  the  different  properties  of  the  species  to 
be  isolated.  Thus,  the  germs  of  the  septicsemias  of 
the  rabbit  and  of  the  mouse  have  been  withdrawn 
from  the  mass  of  microbes  which  pullulate  in  blood 
in  way  of  putrefaction,  by  taking  advantage  of  the 
fact  that  these  germs  are  pathogenic  for  such 
animals. 

Pasteur  has  isolated  the  bacillus  anthracis  from 
the  septic  vibrio  in  charbonous  blood  in  a  state  of 
putrefaction  by  taking  into  account  the  fact  that  the 
former  is  aerobic  and  the  latter  anaerobic  :  cultures 
in  the  air  give  the  bacillus  anthracis  only;  those  pro- 
tected from  oxygen  give  the  septic  vibrio. 

The  influence  of  various  chemical  agents  and  that 
of  heat  at  different  degrees  are  also  effectual  means 
of  isolation  ;  they  kill  some  germs  or  considerably  in- 
terfere with  their  multiplication,  and  thus  favor  the 
predominance  of  other  less  sensitive  germs. 

Klebs  has  succeeded  in  isolating  germs  by  basing 
himself  upon  their  unequal  distribution  in  the  liquids 
in  which  they  pullulate.  Some,  immobile,  are  found 
at  the  bottom  or  on  the  walls  of  the  vessels  ;  others, 
motile,  are  uniformly  distributed;  some  again  are 
very  greedy  of  oxygen  and  are  found  in  the  super- 
ficial layer,  ^y  withdrawing  germs  from  these  vari- 
ous parts  more  of  one  species  than  of  another  will 
be  removed,  and  by  repeating  the  operation  several 


128  Manual  of  Veterinary  Microbiology. 

times  in  succession  one  species  will  be  obtained  in  a 
pure  state. 

Cohn  has  separated  certain  germs  by  taking  advan- 
tage of  the  resistance  of  their  spores  to  a  few  mo- 
ments ebullition.  The  bacillus  subtilis,  or  hay  bacil- 
lus, is  obtained  by  boiling  neutral  infusion  of  hay  and 
then  transferring  to  the  incubator.  The  spores  of 
the  bacillus  subtilis  alone  develop  because  these  alone 
have  resisted. 

Germs  can  be  isolated  by  more  direct  means. 

31ethod  of  isolatioii  by  Salmonsen's  capillary  tube. — 
This  author  has  studied,  in  this  way,  the  various 
germs  which  grow  in  putrefactive  blood.  He  aspirated 
defibrinated  blood  into  long  capillary  tubes  which  he 
closed  at  both  ends  and  fixed  upon  a  horizontal  card. 
The  few  germs  which  are  included  in  the  tube  grow 
separately  in  the  different  parts  of  its  length  ;  their 
evolution  can  thus  be  studied  and  the}''  can  be  col- 
lected separately  for  cultivation. 

3Iethod  of  isolation  by  dilution. — A  material,  rich  in 
germs  of  different  kinds,  is  diluted  with  sterilized 
water  so  that  the  germs  are  considerably  rarefied. 
This  liquid  is  then  inoculated  by  drops  into  a  series 
of  culture  vessels  ;  those  of  these  vessels  which  have 
received  only  one  germ  will  give  a  pure  culture  on 
incubation. 

MM.  Roux  and  Yersin  have  succeeded  in  isolating 
the  bacillus  of  human  diphtheria  by  making  with  a 
platinum  wire  charged  with  a  trace  of  false  mem- 
brane, longitudinal  streaks  in  a  series  of  tubes  of 
blood  serum.  The  germs  become  progressively  rare- 
fied on  the  wire  and  ultimately  the   serum  in  the  last 


IletJiods  of  Determination  of  Pathogenic  Blicrobes.  129 

inoculated  tubes  receives  no  more  than  one  2:erm : 
the  culture  is  then  pure. 

Method  of  isolation  by  plate  cultures. — Koch  has  re- 
commended a  method  of  plate  culture  now  practiced 
in  all  the  laboratories.  A  trace  of  the  substance 
containing  the  bacterial  mixture  is  inoculated  to  a 
tube  of  gelatin  which  is  then  fluidified  by  heating  at 
30°.  The  gelatin  is  then  agitated  so  as  to  uniformly 
distribute  the  germs  throughout  its  substance,  and 
poured  upon  a  sterilized  glass  plate  which  is  placed 
horizontally  on  a  cold  surface,  and  covered  with  a 
bell  jar.  The  gelatin  spreads  out  in  a  thin  solid  layer 
in  which  the  germs  find  themselves  isolated.  The 
plate  is  then  placed  on  a  small  bench  in  the  moist 
chamber,  in  a  room  kept  at  a  temperature  of  about 
20°.  Each  germ  gives  an  isolated  colony,  the  appear- 
ance of  which  can  be  studied  and  from  which  seed 
can  be  obtained  for  starting  new  cultures.  In  this 
process  the  germs  which  grow  on  the  surface  of  the 
layer  of  gelatin  and  which  come,  for  the  most  part, 
from  the  exterior  should  not  be  taken  into  account. 

Instead  of  using  a  plate  the  gelatin  may  be  spread 
out  in  the  tube  itself  or  in  any  vessel  presenting  a 
very  large  interior  surface.*  This  mode  of  procedure 
has  the  advantage  over  the  original  technique  that  it 
exempts  the  culture  from  all  risk  of  external  infection 
and  allows  of  anaerobic  cultures. 

The  substitution  of  agar-gelatin  for  gelatin  consti- 

*  [The  original  "plate  process"  of  Koch  is  now,  for  the  most 
part,  supplanted  by  the  more  convenient  and  safer  method  of 
Petri,  in  which  the  fluidified  gelatin,  after  inoculation  in  the  test 
tube,  is  poured  Into  a  shallow  glass  dish  provided  with  a  cover 
(crystallizers) . — D.] 


130  Manual  of  Veterinary  3Iicrohiology. 

tutes  another  improvement,  tlie  first  of  these  sub- 
stances admitting  of  being  raised  to  39°  without 
fluidifying.  The  temperature  of  39°  is  much  more 
favorable  for  the  vegetation  of  germs  than  that  of  20°. 

Inoculation  of  culture  media. 

Inoculation  of  culture  media  should  be  performed 
in  such  a  manner  as  to  avoid  the  introduction  into 
the  culture  medium  of  external  germs,  either  from 
the  air  or  the  surface  of  external  objects.  Air  germs 
will  be  avoided  by  considerably  inclining  the  bulb  or 
tube  to  be  inoculated  toward  the  horizontal  and  ope- 
rating rapidly  but  quietly  so  as  not  to  cause  agitation 
of  the  air.  The  instruments  used  in  transferring  the 
seed  must  first  of  all  have  been  disinfected.  These 
instruments  are  : 

1st.  A  somewhat  rigid  'platinum  wire,  three  to  five 
centimeters  in  length,  fused  to  the  end  of  a  glass 
rod  of  small  diameter.  This  wire  is  brought  to  a  red 
heat  in  the  flame  of  an  alcohol  lamp ;  as  soon  as  it  is 
cooled  the  extremity  is  charged  with  a  trace  of  the 
seed  which  is  then  transferred  to  the  medium  to  be 
inoculated,  shortening  as  much  as  possible  the  course 
to  be  traversed  by  the  wire  in  order  to  diminish  the 
chances  of  infection  from  the  air.  In  the  case  of 
solid  media  the  seed  may  be  deposited  in  a  line  on 
the  surface  or  in  a  vertical  track  into  the  substance 
of  the  gelatinized  mass.  The  appearance  of  the  cul- 
ture will  naturally  vary  with  these  two  modes. 

The  platinum  wire  may  be  replaced  by  a  needle  of 
glass,  readily  obtained  by  drawing  out  a  fusible  glass 
rod  over  the  lamp. 

2nd.  Capillary  tubes. — A  glass  tube  is  drawn  out  in 


Methods  of  Determination  of  Pathogenic  llicrobes.   131 

the  flame  so  as  to  reduce  it  to  capillary  dimensions; 
the  capillary  segment  which  has  been  perfectly  ster- 
ilized by  the  heat  is  then  closed  at  its  two  ends. 
When  used,  it  is  flamed,  the  two  ends  broken  off", 
and  one  of  them  introduced  into  the  liquid  contain- 
ing the  seed,  which  ascends  by  capillarity:  the  tube 
is  then  passed  into  the.  culture  medium  and  a  drop 
of  the  fluid  expelled  by  blowing  at  the  other  end. 
Such  a  tube  can  only  be  used  once. 

3d.  Pasteur's  pipette. — Pasteur  has  designed  a  special 
pipette  for  collecting  and  sowing,  in  a  state  of  purity, 
liquids  containing  germs.  It  consists  of  a  glass  tube 
five  or  six  centimeters  in  length  and  about  one  centi- 
meter in  diameter;  this  tube  is  drawn  out  and  closed 
at  one  of  its  extremities  the  other  being  provided 
with  a  constriction,  and  filled  with  wadding;  the 
whole  is  sterilized  at  150°.  In  using  it,  the  slender 
end  is  flamed,  the  point  broken  oflf,  and  the  fluid  con- 
taining the  seed, — blood,  various  serosities,  urine,  pus, 
cultures,  etc. — aspirated  into  the  tube.  The  pipette  is 
then  introduced  into  the  medium  to  be  inoculated  and 
one  or  two  drops  allowed  to  flow  out.  A  liquid  con- 
taining bacteria  may  be  preserved  in  this  tube  for 
some  time  by  taking  the  precaution  to  seal  the  capil- 
lary extremity  in  the  flame.  The  Pasteur  pipette  can 
be  used  for  sowing  fluid  media  only;  the  platinum 
wire  serves  equally  well  for  both  fluid  and  solid 
media. 

Placing  at  a  suitable  temperature. 

Whilst  most  germs  are  able  to  grow  at  the  tem- 
perature of  15°  to  20°  C,  many  of  them  grow  better 
at  a  temperature  of  30°  to  40°,  and  a  certain  number 
are  able  to  grow  at  this  temperature  only. 


132  3Ianual  of  Veterinary  Microbiology. 

For  cultivation  at  20°  it  is  sufficient  to  place  the 
inoculated  media  in  an  ordinary  room ;  this  room 
should  be  heated  in  winter,  and  in  summer,  on  the 
other  hand,  should  be  protected  from  a  too  free  en- 
trance of  the  sun's  rays.  If  necessary,  a  room  can 
be  provided  with  double  windows  and  padded  door, 
in  which  is  kept  a  stove  receiving  gas  from  a  thermo- 
regulator  placed  in  the  room ;  a  constant  temperature 
can  thua  be  obtained. 

When  the  cultures  require  a  temperature  of  from 
30°  to  40°,  we  have  recourse  to  special  ovens.  These 
are  air  ovens  in  which  a  suitable  temperature  is  main- 
tained. 

Culture  ovens  are  of  various  forms  and  sizes. 
They  may  have  single  or  double  walls;  in  the  latter 
case  the  space  between  these  walls  contains  a  layer 
of  water.  They  are,  further,  furnished  with  an  ar- 
rangement which  permits  of  the  renewal  of  the  in- 
terior air.  These  ovens  may  be  regulated  for  differ- 
ent temperatures;  usually  they  are  heated  to  39°  C. 
Culture  ovens  have  also  been  constructed,  the  tem- 
perature of  which  varies  at  different  levels  but  re- 
mains constant  for  each  of  these. 

Two  principal  conditions  must  be  fulfilled  in  order 
to  maintain  a  constant  temperature;  the  loss  of  heat 
must  be  reduced  to  a  minimum  and  be  invariable, 
and  the  heat  communicated  to  the  apparatus  must  be 
equal  to  the  heat  lost.  The  first  condition  is  obtained 
by  surrounding  the  ovens  with  a  body  which  is  a  bad 
conductor  of  heat,  such  as  felt,  sometimes  by  a 
double  wall  and  a  double  door,  and  by  placing  them 
in  a  room  kept  at  a  uniform  temperature.  As  to  the 
second,  it  requires  a  more  complicated  arrangement; 


Methods  of  Determination  of  Pathogenic  Jlicrobes.   133 

the  gas  taken  from  tlie  pipe  passes  first  into  a  regu- 
lator which  corrects  the  variations  of  pressure  at  the 
gasometer  at  clifterent  periods  of  the  day,  and  then 
arrives  at  the  apparatus  by  passing  through  a  tem- 
perature regulator.  This  last  is  of  various  forms;  it 
is  usually  a  kind  of  mercurial  thermometer  sur- 
mounted by  a  chamber  into  which  the  gas  enters; 
when  the  temperature  rises  in  the  oven  in  which  it 
is  placed,  the  mercury,  in  expanding,  partially  ob- 
structs the  entrance  of  the  gas,  diminishes  the  flow 
and  the  combustion,  and  depresses  the  temperature. 
This  depression  results  in  the  retraction  of  the  mer- 
cury, a  larger  inrush  of  gas,  and  the  temperature 
rises  again:  thus  the  regulation  takes  place  con- 
stantly between  temperatures  so  close  to  each  other 
that  the  oscillations  are  inappreciable. 

The  regulation  of  the  ovens  may  also  be  obtained 
by  the  expansion  of  the  water  between  the  double 
walls.  The  water,  in  heating,  expands,  rises  in  a 
small  tube,  and  presses  against  an  elastic  membrane 
of  caoutchouc  or  thin  metal,  which  membrane  dimin- 
ishes the  orifice  of  entrance  of  the  gas. 

Aerobic  cultures. — All  that  is  needed  in  order  to  ob- 
serve the  development  of  aerobic  germs  is  to  place 
the  inoculated  media  in  the  oven,  or,  as  we  may  now 
call  it,  the  incubator,  at  37°;  this  incubator  is  so  ar- 
ranged that  the  air  in  its  interior  is  continually  re- 
newed. 

All  the  media  admit  of  cultures  being  carried  on 
at  37°.  ISTutritive  gelatin,  however,  being  fluidified 
above  25°,  should  not  be  carried  above  this  tempera- 
ture if  it  is  desired  to  obtain  the  advantages  arising 
from  the  use  of  solid  media. 


134  Manual  of  Veterinary  Microbiology. 

Anaerobic  cultures. — Anaerobic  germs,  in  order  to 
grow,  must  be  protected  from  the  air;  before  attempt- 
ing cultivation,  therefore,  it  is  necessary  to  remove 
the  oxygen  from  the  atmosphere  and  the  medium  in 
which  these  are  expected  to  develop.  This  is  accom- 
plished in  various  ways.  The  best  method  consists 
in  creating  a  vacuum  in  the  culture  apparatus  and 
replacing  the  air  with  carbonic  acid  or  hydrogen. 
This  operation  is  repeated  several  times  in  order  to 
insure  the  complete  removal  of  the  air.  Gelatin 
must  be  fluidified  before  it  is  deoxygenated.  When 
the  operation  is  completed  the  culture  vessel  is  sealed 
in  the  flame. 

The  oxygen  of  the  air  can  be  abstracted  by  sealing 
the  culture  tube  within  a  second,  containing  sub- 
stances which  rapidly  absorb  oxygen,  such  as  pyro- 
gallic  acid  with  the  addition  of  a  solution  of  caustic 
potash.  Sometimes,  also,  we  add  to  the  culture 
media  substances  capable  of  taking  up  oxygen;  for 
example,  neutralized  sulfate  of  indigo.* 

*  [Anaerobic  cultures  can  also  be  conveniently  carried  on  in 
small  closed  tubes  completely  filled  with  culture  medium.  These 
tubes  may  be  filled  in  various  ways;  the  following  method  of 
preparation  and  use  is  that  which  I  have  found  most  satisfactory: 
A  piece  of  glass  tubing  about  h  cm.  in  diameter  and  10  to  15  cm. 
in  length  is  sealed  at  one  end  in  the  flame  of  a  blow-pipe,  heated 
throughout  sufficiently  for  sterilization,  drawn  out  at  the  other 
end  to  a  thickness  of  from  1  to  2  mm.,  and  sealed  at  a  point  about 
6  cm.  from  the  thicker  part  of  the  tube.  The  evacuation  of  the 
air  in  the  tube  is  obtained  by  the  ebullition  of  alcohol.  A  few 
drops  are  allowed  to  ascend  (by  slightly  heating  the  tube,  break- 
ing off  the  point  and  immersing  it  in  the  fluid),  shaken  to  the 
bottom  and  the  tube  then  held  in  the  flame  of  a  Bunsen  burner. 
Long  forceps,  the  points  of  whi(!h  are  wrapped  in  asbestos,  are 
most  suitable  for  this  purpose.    The  essential  points  in  this  process 


Methods  of  Determination  of  Pathogenic  Microbes.    135 

Physical  and  chemical  characters  of  cultures. 

Physical  characters. — When  germs  proliferate  in 
artificial  media  their  cultures  assume  characters 
which  vary  with  the  nature  of  these  germs  and  with 
the  media. 

In  cultures  on  gelatin  plates  the  colonies  assume 
diflerent  aspects.  Sometimes  these  colonies  are  rep- 
are  that  the  heating  be  done  carefully  in  order  to  avoid  breakage 
and  that  the  whole  extent  of  the  tube  be  suiEciently  heated  to 
prevent  condensation  of  the  alcohol  vapor.  As  soon  as  the  alco- 
hol is  completely  volatilized  the  open  end  of  the  tube  is  sealed ;  an 
abrupt  curve  near  the  point  insures  its  breaking  at  the  desired 
place  when  the  tubes  are  to  be  filled.  A  large  number  of  these 
tubes  can  be  made  at  one  time  and  kept  in  stock.  In  making 
bouillon  cultures  the  fluid  contained  in  test-tubes,  or  (for  this 
purpose)  better,  in  small  homeopathic  vials,  is  boiled,  allowed  to 
cool  sufficiently,  and  inoculated  with  the  material  from  which  the 
culture  is  to  be  made.  The  point  of  the  anaerobic  tube,  after 
quick  flaming,  is  broken  off  under  the  fluid  by  contact  with  the  bot- 
tom of  the  vial.  When  the  tubes  have  been  properly  made,  only  a 
very  small  bubble  of  air  should  be  included  with  the  fluid  w^hich 
rushes  in.  The  point  is  then  sealed  in  the  flame,  during  which 
process  a  drop  or  two  of  the  bouillon  is  necessarily  expelled.  By 
the  use  of  gelatin  or  the  agar  and  gelatin  mixture,  and  proper  di- 
lution in  the  usual  way,  these  tubes  are  quite  well  adapted  for 
isolation  of  species.  The  colonies  which  develop  in  the  substance 
of  the  solid  medium  never  become  large  nor  show  as  character- 
istic appearances  as  by  the  plate  method,  but  they  remain  isolated 
and  admit  of  pure  cultures  being  obtained  from  them.  In  exam- 
ining with  the  microscope  or  making  sowings  from  these  colonies, 
I  break  the  tube  near  the  middle,  quickly  flame  one  of  the  seg- 
ments, and  carefully  heat  it  at  the  closed  extremity ;  the  cylinder 
of  solid  nutrient  medium  is  slowly  expelled  and  received  in  a 
sterilized  Petri  dish,  from  which  the  "  fishing"  can  be  performed 
in  the  usual  way.  In  tubes  prepared  in  this  way  strictly  anaero- 
bic species  can  be  cultivated,  while  aerobic  species,  such  as  the 
hay  bacillus,  refuse  to  grow. — D.] 


136  Manual  of  Veterinary  Microbiology. 

resented  bj  small  raised  droplets  of  a  oily  appear- 
ance and  of  various  colors:  white,  yellow,  rose,  red, 
purple.  In  some  cases  they  appear  as  depressed 
points  with  regular  or  sinuous  borders;  sometimes, 
again,  we  see  a  felted  mass  of  filaments  radiating 
around  a  center.  Certain  germs  fluidify  the  gelatin 
and  thus  produce  a  conical  depression,  full  of  fluid, 
in  the  substance  of  the  medium. 

When  these  colonies  are  examined  under  a  low 
magnification  their  surface  is  seen  to  be  sometimes 
smooth,  sometimes  granular,  their  contour  regular  or 
sinuous,  occasionally  bristling  with  filaments.  All 
these  are  peculiarities  which  serve  to  distinguish  the 
various  pathogenic  species. 

In  gelatin  tube-cultures,  if  the  inoculation  has 
been  made  by  puncture  through  the  mass,  the  inocu- 
lation track  may  be  seen  to  become  turbid  and  grad- 
ually increase  in  size;  sometimes  the  germs  also 
grow  on  the  surface  of  the  gelatin  and  spread  them- 
selves out  in  such  a  w^ay  that  the  whole  assumes  the 
shape  of  a  nail.  When  the  growth  fluidifies  the  gel- 
atin around  the  inoculation  track  the  space  which  it 
occupies  takes  the  form  of  a  funnel ;  but  it  also  hap- 
pens that  liquefaction  occurs  progressively  by  zones 
from  the  surface  toward  the  deeper  parts.  Although 
the  inoculation  is  made  in  a  continuous  track  the 
growth  may  only  appear  in  isolated  points;  this  oc- 
curs when  only  a  small  number  of  germs  have  been 
sown.  From  the  inoculation  made  into  the  depth  of 
the  gelatin  a  series  of  tufts  may  radiate  outward, 
thus  giving  the  culture  the  appearance  of  a  cylindri- 
cal brush  or  sw^ab. 

Cultures  upon  the  other  solid  media  may  present 


Methods  of  Determination  of  Pathogenic  Microbes.    137 

similar  variations.  As  these  media  do  not  become 
fluidified  like  gelatin,  they  are  better  adapted  for 
studj'ing  the  evolution  of  the  germ  colonies. 

Some  germs  give  characteristic  cultures  in  certain 
media.  Glanders,  for  instance,  upon  potato,  gives  a 
slimy  looking  culture  with  chocolate  brown  margins; 
charbon,  sown  in  gelatin  by  "  stab "  inoculation, 
grows  in  the  form  of  a  test  tube  brush,  liquefying 
the  nutritive  medium. 

Cultures  in  bouillon  are  no  less  variable.  Some- 
times we  observe  a  uniform  turbidity  which  is  slowly 
deposited,  in  other  cases  clots  of  progressively  in- 
creasing dimensions  floating  in  the  liquid;  sometimes 
a  flocculent  coherent  mass  looking  like  a  piece  of  sat- 
urated wadding  suspended  in  the  liquid  (charbon) ; 
in  still  other  cases,  finally,  we  see  agglomerated  colo- 
nies floating  on  the  surface  of  the  bouillon  like  leaves 
of  the  water-lily  upon  water  (farcy  of  cattle).  These 
various  appearances  evidently  depend  upon  the  mode 
of  association  of  the  germs  of  which  the  culture  is 
composed.  The  long  filaments  take  the  form  of  tufts 
of  hair ;  chains  of  micrococci  that  of  small  pellets  ; 
isolated  micrococci  produce  a  uniform  turbidity  of 
the  fluid. 

Germs  may  change  the  color  of  the  culture  media ; 
such  changes  are  sometimes  sufficient  to  distinguish 
these  germs:  blue  pus.  Anaerobic  germs  often  give 
rise  to  a  disengagement  of  gases  more  or  less  oflensive, 
recalling  those  of  putrefaction. 

Chemical  characters. — The  chemical  reactions  to 
which  the  multiplication  of  germs  gives  rise  natu- 
rally vary  according  to  the  germs  concerned;  they 
12 


138  Manual  of  Veterinary  31icrobiology . 

depend  also  upon  the  special  conditions  in  which 
they  are  placed  (aerobic  and  anaerobic).  The  medium 
becomes  impoverished  in  alimentary  substances,  and, 
at  the  same  time,  becomes  charged  with  excretory 
products.  These  we  have  already  described ;  we  will, 
however,  repeat  that  they  may  be  toxic  for  the  germs 
and  arrest  their  multiplication,  and  that  they  often 
communicate  to  the  media  in  which  they  are  dif- 
fused, certain  pathogenic  properties  which  the  germs 
themselves  possess. 

Preservation  of  cultures. 

The  exhaustion  or  contamination  of  the  media 
speedily  brings  the  germs  to  the  condition  of  latent 
life;  from  that  time  they  cease  to  multiply ;  the  com- 
bined action  of  the  air  and  light  more  or  less  quickly 
destroys  them.  The  virulence  of  a  culture  also  pro- 
gressively diminishes  from  the  same  cause. 

This  annihilation  of  virulence  is  more  or  less 
quickly  produced  according  to  the  germs  concerned, 
and  also  according  to  the  composition  of  the  culture 
medium.  Thus,  we  have  seen  cultures  of  fowl  chol- 
era deprived  of  all  pathogenic  action  for  adult  rab- 
bits after  one  day,  although,  usually,  this  is  preserved 
for  sixty  days,  e^iposed  to  the  air. 

For  the  longer  preservation  of  cultures  of  germs 
they  may  be  inclosed  in  small  sterilized  tubes  which 
are  sealed  by  the  flame  so  as  to  include  as  little  air  as 
possible.  These  tubes  are  kept  in  the  dark  or  in 
wooden  cases,  as  we  are  in  the  habit  of  employing. 
In  this  way  their  preservation  is  lengthened,  but  it 
is  not  indefinite;  after  a  variable  time,  months  or 
years,  the  germs  die ;  in  order  to  preserve  the  seed,  it 


Methods  of  Determination  of  Pathogenic  3Ucrobes.    139 

is  necessary,  from  time  to  time,  to  invigorate  the 
stock  by  making  inoculations  to  susceptible  animals, 
and  from  these  obtain  new  cultures. 

III.  Experimental  infections. 

Pathogenic  germs,  inoculated  to  animals,  may  de- 
termine in  the  latter  troubles  of  various  kinds.  These 
artificial  microbic  diseases  are  occasionally  charac- 
teristic of  certain  germs.  J^evertheless,  a  given 
germ  does  not  always  produce  the  same  morbid  con- 
ditions; these  are  influenced  by  the  animal  species 
used  for  the  inoculation  and  may  also  vary  with  the 
individual;  the  method  of  inoculation  also  has  its 
influence,  and  the  symptoms  observed  may  be  de- 
pendent upon  this  method  ;  the  condition  of  the  virus 
used  as  to  virulence,  and  its  origin  (cultures  or 
pathological  products),  have  also  an  important  bear- 
ing on  the  result  of  the  inoculation ;  finally,  the 
amount  of  the  virus  has  an  important  influence: 
there  are  diseases  which,  inoculated  in  small  doses, 
are  inofiensive  or  produce  immunity  whilst  large 
doses  more  or  less  rapidly  result  in  death. 

All  these  reasons  indicate  that  we  can  draw  no  ab- 
solute conclusions  as  to  the  results  of  the  inoculation, 
and  that  the  latter  is  of  no  value  except  when  com- 
bined with  other  means  of  diagnosis. 

Experimental  inoculations  are  occasionally  made 
with  the  object  of  purifying  an  impure  virus  ;  in  this 
case  advantage  is  taken  of  the  property  possessed  by 
certain  germs  of  developing  in  a  given  animal 
species,  whilst,  the  other  microbes  with  which  they 
may  be  commingled  can  not  live  in  this  species. 

Subjects  of  inoculation. — Many  species   of  animals 


140  Manual  of  Veterinary  31icrobiology . 

may,  in  an  emergency,  be  brought  into  use  for  experi- 
mental inoculation,  but  there  are  some  which  are  pre- 
ferred on  account  of  their  great  susceptibility  for  most 
of  the  bacterial  diseases  and  of  the  ease  with  which 
they  can  be  obtained. 

The  animals  which  are  the  most  used  are  the 
guinea  pig,  rabbit,  rat,  mouse,  chicken,  pigeon,  and 
small  birds.  In  exceptional  cases  the  large  domes- 
ticated animals  are  employed. 

Inoculation  ' substances.— YvYxilQui  substances  used 
for  inoculation  should,  as  far  as  possible,  be  free  from 
all  microbic  mixture,  and  the  Pravaz  syringe  and 
other  inoculation  instruments  should  previously  be 
rendered  aseptic. 

If  the  product  to  be  inoculated  is  a  bouillon  culture, 
this  fluid  is  turned,  after  shaking,  into  a  previously 
flamed  watch  glass,  and  quickly  aspirated  into  the 
syringe. 

If  the  culture  has  been  made  upon  a  solid  medium 
a  quantity  of  the  material  is  taken  upon  a  sterilized 
l)latinum  wire  and  diluted  in  a  little  sterilized  water 
or  bouillon. 

"When  we  have  to  do  with  fluid  pathological  pro- 
ducts (blood,  milk,  pus,  etc.)  these  products,  col- 
lected in  a  pure  state  from  the  living  being  or  from 
the  cadaver,  are  employed  in  the  way  just  described. 
In  some  cases  they  are  previously  diluted. 

Sometimes  the  virulent  substance  is  a  solid  patho- 
logical product.  This  product,  free  from  all  con- 
tamination, is  crushed  in  a  special  mortar,  diluted  in 
bouillon,  which  is  then  strained  through  fine  linen. 
To  more  com.pletely  avoid  the  external  germs  the 
virulent  particle   may   be   introduced  into   a    small 


Methods  of  Determination  of  Pathogenic  Microbes.  141 

previously  sterilized  tube,  and  crushed  by  means  of 
a  flamed  glass  rod,  the  diameter  of  which  is  a  little 
smaller  than  that  of  the  interior  of  the  tube ;  steril- 
ized bouillon  is  then  added,  and,  after  the  particles  in 
suspension  have  been  deposited,  it  is  aspirated  into 
the  syringe. 

Methods  of  inoculation. — The  virus,  thus  prepared, 
may  be  used  for  inoculations  performed  in  various 
ways,  which  we  will  now  review. 

1.  Endermic  inoculations. — This  is  the  simplest 
method  of  inoculation ;  in  its  performance  all  that  is 
necessary  is  to  lay  bare  the  deeper  layer  of  the  epi- 
dermis without  exciting  much  hemorrhage,  and  there 
apply  the  active  substance. 

The  hair  is  clipped  from  the  region  to  be  inocu- 
lated, a  series  of  closely  approximated  superficial 
scarifications  made  with  a  bistoury,  and  the  virulent 
substance  spread  over  it.  For  this  inoculation  regions 
of  the  body  should  be  selected  which  are  not  easily 
reached  by  licking,  rubbing,  etc. 

2.  Subcutaneous  inoculation. — The  object  of  this  in- 
oculation is  to  introduce  the  active  product  into  the 
subcutaneous  cellular  tissue.  A  fold  of  the  skin  hav- 
ing been  pinched  up,  the  canula  of  the  syringe  is  in- 
troduced at  its  base  and  the  liquid  to  be  inoculated 
slowly  expelled.  It  is  sometimes  desirable  to  free 
the  region  from  hair  or  feathers  and  render  the  point 
of  inoculation  aseptic,  by  the  application  of  a  strongly 
heated  glass  rod.  The  inoculation  having  been  made, 
the  canula  is  withdrawn,  and,  in  order  to  render  the 
result  more  certain  and  more  rapid,  the  inoculated 
point  is  manipulated  so  as  to  lacerate  the  cellular  tis- 
sue and  accelerate  absorption. 


142  Manual  of  Veterinary,  3Iicrobiology. 

Inoculations  may  be  made  in  any  region,  but, 
preferably,  in  places  where  the  skin  is  thin  and  pliant 
(internal  face  of  the  thighs,  abdominal  wall,  pectoral 
region  in  birds),  and  the  celhilar  tissue  abundant. 

3.  Intra-peritoneal  inoculations. — In  order  to  intro- 
duce the  virulent  matter  into  the  abdomen,  the  ani- 
mal being  held  well  on  the  back,  the  abdominal  walls 
are  pinched  up  between  the  thumb  and  index,  and 
the  operation  continued  as  above,  after  being  well  as- 
sured that  the  point  of  the  syringe  is  indeed  free 
within  the  abdomen.  It  is  necessary  here  to  operate 
with  a  certain  amount  of  care  in  order  to  avoid 
wounding  the  viscera  an  accident  especially  to  be 
feared  in  birds. 

4.  Intra-venous  inoculation. — This  method  necessi- 
tates the  employment  of  a  liquid  free  from  solid  par- 
ticles which,  by  their  arrest  in  the  smaller  vessels, 
might  occasion  fatal  embolisms.  In  performing  this 
inoculation  the  vein  is  distended  by  pressure  exerted 
on  its  course  and  the  canula  introduced  into  it,  the 
point  directed  toward  the  heart ;  the  operation  is  suc- 
cessful when  a  drop  of  blood  issues  at  the  shoulder 
of  the  canula;  a  graduated  pressure  is  then  brought 
to  bear  on  the  piston. 

For  this  inoculation  the  most  salient  superficial 
veins  are  selected,  in  the  rabbit  the  veins  of  the  ear, 
in  birds  the  vein  of  the  arm.  In  some  animals  the  in- 
oculation can  be  made  into  the  jugular,  saphena,  etc. 

5.  Inoculations  in  the  anterior  chamber  of  the  eye. — 
The  eye  is  first  ansesthized  by  means  of  a  few  drops 
of  a  solution  of  cocaine,  at  1  to  20;  then,  the  globe 
beinsf  immobilized,  the  canula  is  insinuated  horizon- 
tally  through  the  cornea  in  its  eccentric  part.     One 


Methods  of  Determination  of  Pathogenic  Microbes.  143 

or  two  drops  of  the  liquid  are  then  expelled  and 
may  be  seen  diffusing  themselves  in  the  transparent 
media. 

6.  Intra- cranial  inoculations.— It  is  necessary  here, 
in  the  first  place,  to  trephine  the  cranium,  an  opera- 
tion which  necessitates  a  variety  of  instruments.  In 
small  animals,  however,  the  operation  can  be  very 
simply  performed.  The  animal  being  made  fast,  an 
incision  is  made  in  the  skin  over  the  frontal  bone  out- 
side of  the  median  line,  the  periosteum  is  crucially 
divided  and,  with  the  point  of  a  strong  bistoury  held 
vertical  to  the  surface  of  the  bone,  a  small  opening  is 
made  by  rotating  the  instrument  upon  itself. 

When  the  opening  is  considered  to  be  of  sufficient 
size  the  canula,  thoroughly  sterilized,  is  introduced 
under  the  cerebral  envelopes  and  a  few  drops  of  the 
liquid  injected. 

Inoculations  may  also  be  made  into  the  various 
serous  cavities,  the  trachea,  muscles,  etc.,  but  the 
technique  of  these  operations  needs  no  special  de- 
scription. 

Besides  these  contagions  by  inoculation,  an  organ- 
ism may  also  be  artificially  infected  by  the  methods 
of  ingestion  or  inhalation  of  virulent  products.  These 
methods  o-ive  results  relutivelv  less  certain. 

Collection  of  virulent  products. — Pathological  prod- 
ucts can  be  collected  either  from  diseased  animals  or 
from  their  cadavers. 

On  diseased  animals  the  process  differs  according  as 
it  is  desired  to  collect  a  liquid  (blood,  pus,  etc.)  or  a 
solid  particle.  Great  precautions  should  always  be 
taken  in  order  to  avoid  the  common  germs  which 
surround  us.     After  the  region  hns  been  shaved  it 

OP  THE 


144      •      3Ianual  of  Veterinary  Microbiology. 

must  be  sterilized  by  means  of  a  strongly  heated 
glass  rod.  The  solid  part  which  it  is  desired  to  study 
is  then  extracted  with  flamed  instruments;  liquids 
are  aspirated  into  the  Pasteur  pipette. 

On  cadavers  the  same  precautions  are  necessary.  It 
must  be  remembered  that,  in  contagious  diseases,  de- 
composition usually  proceeds  very  rapidly  and,  in 
consequence,  the  organism  soon  becomes  invaded  by 
the  germs  of  putrefaction.  The  cadaver  having  been 
fixed  in  the  proper  position,  the  autopsy  must  be  con- 
ducted in  a  methodical  manner  and  the  products, 
solid  or  liquid,  which  it  is  desired  to  study  must  be 
collected  aseptically. 

It  should  not  be  forgotten  that  the  disease  in  ques- 
tion is  a  contagious  one,  and  that  no  part  of  the  ani- 
mal should  escape  the  destruction  which  ought  to 
follow  all  autopsies  of  this  kind;  it  is  well,  also,  to 
remark  that  several  microbic  diseases  are  transmissi- 
.ble  to  man;  the  operator,  therefore,  should  take  the 
precaution  to  protect  himself  against  infection. 

Solid  products,  when  collected,  should  immediately 
be  used  for  inoculations  and  for  cultures,  or  should  be 
inclosed  in  sterilized  tubes.  Liquids  should  be  sealed 
in  the  Pasteur  pipettes  in  which  they  have  been  col- 
lected. 


Microbic  Diseases  Individually  Considered.      145 


PART   THIRD. 

MICROBIC  DISEASES  INDIVIDUALLY  CONSID- 
ERED. 


I. 


Microbic  diseases  consecutive  to  wounds. 

Surgical  wounds,  treated  strictly  according  to  anti- 
septic rules,  are  protected  from  pathogenic  germs; 
they  heal  without  excessive  swelling  and  without 
suppuration  or  fever.  The  healing  process  is  limited 
to  the  extent  of  cell  proliferation  necessary  for  repa- 
ration only.  It  is  the  same  with  accidental  wounds 
when  they  are  rendered  aseptic;  but  if,  by  the  con- 
tact or  the  subsequent  action  of  the  object  causing 
the  injury,  or  by  contact  with  clothing  of  any  kind, 
harness,  litter,  water,  or  the  atmosphere,  pathogenic 
germs  are  introduced  into  the  wound,  diverse  patho- 
logical changes  may  be  observed. 

"We  have  seen,  in  the  general  part  of  this  work, 
that  a  number  of  pathogenic  germs,  for  example, 
those  of  suppuration  and  septicaemias  are  encountered 
almost  everywhere  ;  we  meet  with  them  also  in  most 
of  the  morbid  conditions  which  complicate  wounds ; 
these  diseases  we  shall  iirst  of  all  consider. 

The  lesions  of  a  microbic  nature  which  develop 
consecutive  to  wounds  are  local,  remote,  or  general. 
13 


146  3Ianual  of  Veterinary  Microbiology. 

Local  lesions  consist  of  inflammatory  processes  the 
predominant  character  of  which  depends  principally 
on  the  special  pathogenic  property  of  the  microbes 
contained  in  the  wound;  these  processes  may  be  es- 
sentially exudative ;  inflammatory oedemas,  erysipelas;  or 
suppurative  :  superficial  suppuration,  abscess,  phlegmon; 
or  hypertrophic  :  actinomycomata,  botryomycomata ,  an- 
atomical tubercles:  or,  finally,  gangrenous:  traumatic 
gangrene,  diphtheria,  hospital  gangreiie.  The  dominant 
character  of  these  inflammations  depends  principally, 
but  not  exclusively,  on  the  special  nature  of  the  germs 
distributed  upon  the  wounds;  in  reality, the  reaction- 
ary powers  of  the  tissues  have  also  their  influence 
here,  and  a  given  germ,  the  streptococcus  of  erysipe- 
las for  example,  will  occasion  sometimes  a  simple 
dermatitis  with  interstitial  and  superficial  exudation 
under  the  form  of  vesicles,  phlyctenae  (erysipelas), 
sometimes  it  will  determine,  in  addition,  a  deep  seated 
suppuration  (phlegmonous  erysipelas),  and  even  ne- 
crosis of  the  inflamed  tissues  (gangrenous  erysipelas). 

Remote  lesions  manifest  themselves  in  the  organs 
in  direct  or  vascular  continuity  with  the  tissues  orig- 
inally attacked.  Hence,  we  see  peritonitis  occur 
consecutive  to  changes  of  a  microbic  nature  located 
in  the  abdominal  viscera:  wounds  of  the  intestine, 
of  the  uterus,  metritis,  etc.  In  respect  to  vascular 
continuity,  this  involves  alterations  of  the  correspond- 
ing lymphatics  and  blood  vessels  {lymphangitis,  adenitis, 
phlebitis,  endocarditis,  thrombic  and  embolic  lesions). 

Finally,  as  general  troubles,  we  have  pycemia  and 
surgical  septiccemias. 


Microhic  Diseases  Individually  Considered.       147 

Suppuration. 

We  find  in  pus,  besides  the  cells  which  constitute 
its  essential  part,  various  species  of  microbes.  Their 
constant  presence  in  suppurative  inflammations  led  to 
the  supposition  that  suppuration  was  only  produced 
through  the  agency  of  microbes.  This  theory  was 
further  supported  by  the  results  of  experimentation; 
thus,  subcutaneous  injection  of  irritating  substances 
previously  rendered  aseptic  caused  an  inflammation 
corresponding  to  the  irritating  power  of  these  sub- 
stances, but  a  non-purulent  inflammation.  Diapede- 
sis  of  the  white  corpuscles  of  the  blood  seemed  there- 
fore to  be  dependent  upon  the  presence  of  microbes. 

Similar  experiments,  however,  have  led  to  contrary 
results  in  the  hands  of  other  investigators,  and  sup- 
puration has  been  produced  by  means  of  chemical 
substances  (croton  oil,  oil  of  turpentine,  silver  nitrate, 
mercury,  cadaverin,  etc.)  without  the  intervention  of 
bacteria.  Moreover,  it  has  been  found  that  the  ster- 
ilized cultures  of  the  staphylococcus  pyogenes  as 
surely  determine  an  abscess  as  the  staphylococcus 
itself;  the  pus  of  this  abscess,  however,  is  not  itself 
pyogenic.  Substances  with  special  pyogenic  proper- 
ties have,  in  addition,  been  extracted  from  cultures 
of  the  bacilli  of  glanders,  tuberculosis,  charbon  and 
of  Friedlander's  pneumococcus.  Thus  is  explained 
the  possibility  of  spontaneous  abscesses  the  pus  of 
which  is  free  from  microbes;  the  latter,  in  such  case, 
are  present  in  another  part  of  the  economy  and  the 
pyogenic  substances  which  they  secrete  being  ab- 
sorbed, we  can  understand  that  they  may  determine 
purulent  inflammation  of  a  predisposed  organ  or 
tissue. 


148  Manual  of  Veterinary  Microbiology. 

These  considerations,  important  as  they  are  from  a 
theoretical  point  of  view,  have,  in  practice,  only  a 
secondary  interest.  Under  natural  conditions  suppur- 
ation is  really  always  the  result  of  microbes,  acting 
not  of  themselves,  as  was  at  first  supposed,  but,  ac- 
cording to  recent  researches,  by  means  of  the  toxines 
to  which  their  nutritive  exchanges  give  rise.* 

The  rational  application  of  antiseptics  in  the  dress- 
ing of  wounds  has,  further,  to  a  large  extent,  demon- 
strated this  truth,  in  making  union  by  first  intention 
the  necessary  termination  of  operative  wounds. 

The  most  common  bacteria  of  suppuration  are : 
the  staphylococcus  -pyogenes  aureus  (yellow  pus) ; 
the  staphylococcus  pyogenes  albus  (white  pus) ; 
the  staphylococcus  p^yogenes  citreus; 
the  streptococcus  pyogenes, 
and  several  other  species,  including  a  bacillus — the 
bacillus  pyogenes  septicus. 

These  are  met  with  in  the  various  suppurative 
processes:  phlegmons,  abscesses  and  the  effusions  of 
pysemia,  purulent  inflammations  of  the  external  and 
internal  surfaces,  etc. 

The  yellow  staphylococcus  has  also  been  found  in 
furuncles  and  malignant  pustule;  the  particular  char- 
acters of  these  diseases  seem  to  depend  on  the  mode 
of  penetration  and  the  localization  of  the  pyogenic 
germs  rather  than  on  the  special  nature  of  the  latter. 
We  have  ourselves  encountered  the  staphylococcus 
albus  in  furuncles  which  had  developed  in  large  num- 

*  [According  to  Bucliner's  investigations,  the  pyogenic  property 
of  sterilized  cultures  of  many  bacterial  species  resides  in  the  bac- 
teria themselves,  and  not  in  the  chemical  products  which  they 
secrete. — D.] 


Microbic  Diseases  Individually  Considered.      149 


bers  on  the  back  of  a  colt  a  few  weeks  old,  and 
which  was  successfully  treated  in  the  college  hos- 
pital. 

The  streptococcus  pyogenes  seems  to  be  also  the 
causative  agent  in  erysipelas  and  pt^erpera^/euer  under 
its  various  forms ;  at  least,  the  streptococcus  of  these 
two  diseases  can  not  be  satisfactorily  diflerentiated 
from  that  which  we  are  now  considering. 

The   streptocooccus  pyo-  -p.    g 

genes  is  widely  distributed 
and  its  virulence  is  subject 
to  great  variations;  when 
injected  to  animals,  and  es- 
pecially to  the  rabbit,  it 
most  frequently  gives  rise  • 
to  a  local  abscess,  but  it  can 
also,  like  the  staphylococcus 
pyogenes,  occasion  multiple 
abscesses    in    the    muscles,  — •** 

kidney,  lung,  etc.,  and  more      Streptococci  in  pus  of  closed 

,     "^        .^\^■  1        ,  abscess  of  horse.    X  1,000.— D. 

or  less  quickly  bring  about 

a  fatal  termination.  The  staphylococcus  aureus  is 
encountered  still  more  frequently  than  the  strepto- 
coccus. 

Cultures. — The  pyogenic  germs  are  easily  culti- 
vated in  the  different  media ;  the  three  staphylococci 
are  distinguished  from  each  other  by  the  color  of 
their  cultures,  the  aureus  giving  a  golden  yellow 
color,  the  alhus  a  white  color,  and  the  citreus  a  citron 
yellow  color. 

The  staphylococci  pyogenes  are  aerobic  ;  the  strep- 
tococcus is  rather  anaerobic. 

The  chemical  study  of  cultures  of  the  staphylococ- 


150  Manual  of  Veterinary  31icrohiology. 

cus  aureus  has  led  to  the  discovery  of  a  non-toxic  pto- 
maine, a  non-nitrogenous  phlogogenic  and  pyogenic 
substance  called  j^hiogosine,  and  a  diastase  also  pyoge- 
nic. The  yellow  coloring  matter  is  only  developed  in 
contact  with  the  air. 

Research  and  coloration. — In  order  to  bring  into 
view  the  microbes  of  pus  it  suffices  to  stain  the  latter 
on  cover  glasses  for  a  few  seconds  with -a  hydro-alco- 
holic solution  of  gentian  violet.  The  Gram  reaction, 
which  they  all  sustain,  admits  of  obtaining  double 
coloration.  "We,  by  this  means,  see  the  microbes  be- 
tween, and  often  even  inside,  the  pus  corpusles. 

Etiology. — The  germs  of  pus  most  frequently  pene- 
trate into  the  tissues  through  a  solution  of  continuity, 
but  they  may  also  invade  the  organism  when  the 
skin  is  intact ;  this  has  been  demonstrated  by  Garre ; 
frictioning  of  the  arm  with  a  culture  of  staphylococcus 
aureus  caused,  on  the  same  day,  the  eruption  of 
furuncular  pustules.  IN'umerous  examples  of  this 
truth  are  furnished  by  veterinary  accoucheurs,  in 
whom  the  arm  becomes  covered  with  pustules  as  a 
result  of  their  intervention  in  difficult  parturition 
or  in  removal  of  the  placenta.  In  this  case  the  le- 
sions always  develop  at  a  pilo-sebaceous  follicle, 
through  the  orilice  of  which  the  purulent  germs  have 
entered.  Finally,  the  germs  of  pus  may  gain  the 
tissues  by  traversing  the  normal  mucosa. 

The  pyogenic  germs  which  we  have  just  referred 
to  are  not  the  only  ones  which  can  give  rise  to  the 
formation  of  pus.  A  number  of  others  possessing 
specific  virulent  properties  have,  in  addition,  the 
power  of  exciting  suppuration  ;  among  these  are  the 
Koch   bacillus,  the  bacillus  of  glanders,  the  actino- 


Microbic  Diseases  Individually  Considered.       151 

mj'ces,  the  bacillus  of  cattle  farcy,  the  bacillus  of 
chicken  cholera  in  the  guinea  pig,  the  bacillus  of 
typhoid  fever,  etc.  These  bacteria,  incidentally  pyo- 
genic, have  been  qualified  as  yyocolic ;  they  act  by 
themselves  or  by  preparing  the  field  for  the  pyogenic 
germs  properly  so  called.  It  may  be  further  stated, 
in  this  connection,  that  the  mere  contact  of  pyogenic 
microbes  with  a  wound  or  living  tissue  is  not  invari- 
ably followed  by  suppuration.  Here,  the  number  of 
microbes  as  well  as  the  resistance  of  the  tissue  or  of 
the  organism  to  which  the  latter  belongs,  all  enter 
into  the  question.  It  is  a  matter  of  common  obser- 
vation that  even  a  simple  wound  in  some  individuals, 
if  left  to  itself,  will  always  come  to  suppuration.  The 
adjuvant  action  of  traumatisms,  irritant  liquids,  and 
individual  predisposition  has,  here,  an  important 
bearing,  modifying  the  resistance  of  the  tissues  toward 
pyogenic  germs. 

The  action  of  pyogenic  germs  can  be  experiment- 
ally aided  by  the  injection  of  their  culture  products. 
Thus,  the  filtered  cultures  of  the  staphylococcus  and 
streptococcus  pyogenes  contain  adjuvant  substances 
and  vaccinatinor  substances.  The  first  are  the  most 
active  and  alone  show  their  efl'ects  when  these  filtered 
cultures  are  injected;  but  they  are  destroyed  by 
twenty-four  hours  exposure  to  55°  in  the  case  of  the 
staphylococcus,  and  to  110°  for  the  streptococcus,  and 
the  injection  of  cultures  thus  heated  confers  immunity. 
According  to  Courmont  and  Dor,  the  adjuvant  action 
of  filtered  cultures  of  the  streptococcus  endures  for 
at  least  three  months. 

Blue  pus — Pus,  in  the  human  being,  occasionally 
exhibits  a  peculiar  blue  color;  this  is  the  result  of  a 


152  Manual  of  Veterinary  Microbiology. 

special  polymorphic  microbe,  generally  assuming  the 
form  of  a  short  curved  bacillus,  occasionally  that  of 
a  micrococcus  or  even  of  a  spirillum. 

The  germ  of  blue  pus  is  very  easily  cultivated  ;  it 
communicates  to  the  nutritive  media  a  green  color; 
by  the  action  of  chloroform  it  is  possible  to  isolate 
form  its  cultures  pyoeyanine  which  is  the  blue  color- 
ing matter  characteristic  of  the  germ.  The  green 
color  of  the  cultures  results  from  the  fact  that  the 
nutritive  media  have  originally  a  yellowish  color. 

When  iujected  to  animals  it  does  not  cause  suppu- 
ration ;  but  its  cultures  are,  nevertheless,  pathogenic 
for  the  rabbit  to  which  it  gives  a  special  disease,  the 
pyocyanic  disease,  acute  or  chronic  according  to  the 
dose  employed,  and  characterized  by  paralysis,  fever, 
albuminuria,  and  diarrhoea. 

The  microbe  of  blue  pus  has  been  encountered  in 
our  animals  only  by  M.  Cadeac,  in  the  spleen  and 
lymph  glands  of  a  dog  killed  in  the  last  stage  of 
lymphadenoma.  The  author  tested  its  identity  by 
culture  methods  and  inoculations  but  did  not  succeed 
in  transmitting  the  disease  to  the  dog ;  he  thinks  that 
the  abnormal  debility  of  the  lymphadenomic  subject 
facilitated  the  installation  of  the  germ  of  the  pyocy- 
anic disease. 

Py(Emia. 

The  knowleage  which  we  now  possess  of  recep- 
tivity and  the  conditions  which  determine  it,  as  well 
as  of  the  situation  of  the  pyogenic  germs  in  the 
meshes  of  the  connective  tissue  in  cases  of  phlegmon, 
justifies  us  in  asserting  that  the  passage  of  these 
germs  into  the  circulatory  fluids  is  probably  a  com- 
mon  but  generally   inoffensive  occurrence.     If  the 


31icrohic  Diseases  Individually  Considered.       153 

organism  should  suffer  from  any  serious  disturbance, 
or  if,  in  consequence  of  a  special  local  alteration,  these 
germs  should  penetrate  in  large  numbers  into  the 
blood,  their  influence  will  cease  to  remain  limited  to 
their  original  focus  and  we  will  see  the  irruption  of 
that  formidable  disease,  pyaemia.  This  disease  is  not 
absolutely  dependent  upon  the  existence  of  a  wound; 
it  can  originate  in  the  course  of  a  purulent  visceral 
inflammation  or  even  appear  spontaneously.  In  this 
last  case  the  microbes  come  either  from  the  mucous 
membrane  or  from  an  old  latent  focus. 

Besides  the  immediate  general  phenomena,  such  as 
those  of  a  peculiarly  intense  fever,  the  arrest  and 
multiplication  of  the  pyogenic  germs  in  different 
parts  of  the  circulatory  apparatus  lead  to  the  produc- 
tion of  metastatic  abscesses  and  purulent  collections 
in  the  natural  cavities.  The  pyogenic  germs  com- 
municate to  the  blood  corpuscles  a  certain  degree  of 
viscidity;  the  latter  become  agglutinated  and,  as  a 
result,  embolisms  occur  in  the  small  arterioles  of  one 
or  more  organs  :  kidney,  liver,  lungs,  muscles,  etc. 
The  microbes  arrested  at  these  embolisms  form  the 
starting  point  of  so  many  foci  of  suppuration. 

In  reality  pysemia   is   rarely  simple ;    along  with 

the  bacteria  of  pus  the  blood  generally  receives  other 

inicrobes  from  wounds  exposed  to  the  air,  and  there 

results  a  concomitant  disease  of  a  septicsemic  order. 

We  shall  see,  further,  that  the  organisms  of  pus  maj', 

under  certain  circumstances,  give,  of  themselves,  a 

pure  septicaemia. 

Septiccemia. 

In  a  general  way  this  name  is  given  to  the  patho- 
logical condition  which  follows  penetration  of  putrid 


154  Manual  of  Veterinary  Microbiology. 

matters  into  the  system.  We  now  know,  however, 
that  putrefaction  is  only  a  complex  fermentation 
tending  to  the  degradation  of  organic  matter,  with 
or  without  the  production  of  fetid  odor,  a  process 
which  necessitates  the  intervention  of  germs  or  mi- 
crobes of  various  species.  Hence  we  can  not  con- 
ceive of  septicaemia  without  microbes. 

But  the  r6le  of  the  latter  has  not  always  the  same 
importance ;  the  germs,  remaining  intrenched  outside 
the  tissues  upon  a  wound,  for  example,  act  solely 
through  the  soluble  products  (ptomaines  and  dias- 
tases) to  which  their  nutritive  exchanges  give  origin, 
and  we  then  have  to  do  with  a  kind  of  poisoning ;  or, 
the  same  germs,  breaking  the  barrier  which  the  liv- 
ing tissues  oppose  to  them,  make  their  way  into  the 
latter  and  multiply  there;  intoxication  by  toxines 
then  becomes  complicated  with  troubles  caused  by 
this  proliferation. 

The  first  of  the  two  contingencies  which  we  have 
just  mentioned  occurs  under  a  multitude  of  condi- 
tions. And,  first  of  all,  it  is  unquestionable  that  sep- 
ticaemia sometimes  can  be  produced  without  the  pres- 
ence of  microbes.  Koch  has  shown  that  five  drops 
of  a  putrefying  fluid  kills  a  mouse  in  a  few  hours,  no 
microbes  then  being  found  either  in  the  blood  or  vis- 
cera. The  disease  thus  developed  is  a  true  intoxica- 
tion by  soluble  microbic  substances  or  ptomaines  en- 
gendered outside  of  the  organism  in  the  putrefying 
fluid.  It  is  to  this  species  of  septicaemia  that  we 
must  refer  the  intoxications  which  result  in  animals 
and  man  from  the  consumption  of  imperfectly  pre- 
served foods  in  way  of  decomposition  or  already 
decomposed ;    such,   for   example,  as   the   poisoning 


Microbic  Diseases  Individually  Considered.       155 

ihotulisme)  which  occurs  in  the  human  species  from 
the  use  of  so-called  Boulogne  sausage  prepared  hy 
unscrupulous  dealers  from  the  flesh  of  animals  which 
have  died  or  been  slaughtered,  diseased  or  sound,  but 
nearly  always,  under  the  mask  of  seasoning,  already 
abandoned  to  the  sway  of  microscopic  life  which  not 
only  uses  up  its  substantial  parts,  but  elaborates  di- 
verse ptomaines  of  formidable  toxic  power. 

At  other  times  septicaemia  is  a  sort  of  auto-intoxi- 
cation, the  septic  poisons  being  elaborated  within  the 
economy  itself  but  upon  a  limited  surface  which  the 
microbes  do  not  break  through,  either  by  reason  of 
their  special  properties  (the  anaerobes  are  unable  to 
live  in  the  blood  during  life),  or  because  the  toxicity 
of  the  products  secreted  and  absorbed  is  such  that 
death  supervenes  in  too  short  a  time  to  allow  of 
the  invasion  of  the  circulatory  fluids;  this  surface  is 
most  frequently  the  seat  of  a  morbid  microbic  pro- 
cess :  for  example,  a  septic  wound,  puerperal  metritis, 
gangrenous  pneumonia,  etc. 

But  the  germs  of  the  intestine  may  give  rise  to 
troubles  even  in  the  absence  of  special  alterations  of 
the  mucosa.  This  takes  place  when  their  products  of 
denutrition — ptomaines,  indol,  skatol,  gaseous  prod- 
ucts, etc. — instead  of  being  eliminated  by  way  of  the 
rectum,  are  absorbed  by  the  blood.  The  chemical 
poisoning  which  then  results  has  received  the  names 
stercorcemia  and  intestinal  septicasmia.  This  poison- 
ing supervenes  under  a  number  of  pathological  con- 
ditions, especially  when  the  gastric  juice  is  insuffi- 
cient in  quantity  or  in  acidity  to  neutralize  the  ma- 
jority of  the  germs  which  pass  through  the  stomach, 


156  Manual  of  Veterinary  Microbiology. . 

and,  in  a  general  manner, in  all  somewhat  lengthened 
diseases  which  lead  to  a  prolonged  retention  of  fsecal 
matters  in  the  intestine  (fever,  inappetence,  retention 
of  bile,  etc.).  The  indication,  in  these  conditions, 
is  to  retard  the  intestinal  fermentations  by  the  ad- 
ministration of  special  antiseptics,  and  to  assist  in 
the  evacuation  of  the  toxic  substances  and  the  germs 
which  produce  them,  by  means  of  purgatives.  This 
evacuant  action  of  laxatives  explains  their  utility  in 
all  febrile  affections  in  which,  for  special  reasons, 
these  remedies  are  not  contra-indicated. 

The  pathogeny  of  septicaemia,  therefore,  is  not  of 
one  kind  only.  The.  nosological  extent  of  the  term 
septicaemia  is,  moreover,  very  imperfectly  defined. 
When  we  take  into  account  the  fact  that  bacteria 
contribute  in  a  general  way  to  the  reduction  of  com- 
plex organic  molecules  to  forrhulse  more  and  more 
simple,  and,  on  the  other  hand,  consider  the  difficulty 
of  determining,  in  this  immense  work  of  microbes, 
what  should  be  regarded  as  putrefaction,  and  what 
definition  should  be  given  of  putrid  matters,  we  must 
recognize  that,  from  the  mode  of  action  of  the  germs 
which  occasion  them,  as  well  as  by  their  evolution, 
all  general  diseases  of  a  microbic  order  ought  to  be 
included  in  the  group  of  septicsemic  affections.  If  a 
certain  number  of  these  have  been  placed  apart,  this 
is  on  account  of  the  specific  characters  of  their  germ 
which,  giving  to  the  disease  a  special  expression,  have 
established  for  it  a  well  defined  morbid  entity:  char- 
bon,  typhoid  fever,  tetanus,  etc. 

Prof.  Degive  had  already  twenty  years  ago  con- 


Microbic  Diseases  Individually  Considered.      157 

ceived  and  clearly  expressed  this  manner  of  view  in 
several  reports  and  discussions. (1) 

He  recognized  in  these  diseases  actual  points  of 
consanguinity  which  led  him  to  refer  them  all  to  the 
same  stock  and  to  regard  them  as  children  of  the 
same  family,  "  The  septoid  stock  or  family,  also  called 
septicaemia^  but  better  designated  septose,  the  septic  or 
jmtiid  diathesis."  If  the  discovery  of  the  special 
germs  of  most  of  these  diseases  no  more  allows  of 
belief  in  their  identity,  it  removes  all  doubts  as  to 
their  analogy. 

The  name  saprcemia  has  been  reserved  for  septicae- 
mias engendered  by  microbes  which  develop  a  strong 
odor  of  putrefaction. 

Septicsemia  was  formerly  considered  only  as  a  com- 
plication of  wounds,  but  it  can  occur  independent  of 
all  traumatism,  the  agents  which  occasion  it  pene- 
trating by  one  of  the  natural  surfaces  without  the  aid 
of  any  solution  of  continuity,  as,  for  instance,  by  the 
digestive,  respiratory,  genital,  urinary  passages,  etc. 
There  are,  therefore,  surgical  septiccernias  and  medical 
septiccemias. 

When  septicaemia  develops  in  consequence  of  a 
traumatism  we  see  in  the  latter  important  changes 
supervene  which  indicate  the  infection  of  the  wound 
by  germs :  the  secretion  becomes  sero-sanguinolent, 
often  fetid,  the  granulations  become  less  firm,  pulta- 
ceous,  often  purple ;  the  neighboring  tissues  swell 
and  become  the  seat  of  an  inflammatory  oedema,  fre- 
quently progressive ;    these  local  lesions  may  entail 

(1)  See  Annales  de  medicine  Veterinaire,  1874,  p.  502;  1875,  p. 
94,  and  1876,  p.  115. 


158  Manual  of  Veterinary  Microhioloyy. 

very  serious  disorders,  such  as  gangrene  and  detach- 
ment of  the  adjoining  tissues;  sometimes  an  actual 
putrefaction  estabUshes  itself  in  the  living  animal  on 
the  part  invaded  by  the  germs.  We  can  not,  how- 
ever, assign  any  fixed  rule  as  to  the  importance  of  the 
local  troubles ;  they  manifestly  depend  upon  the  na- 
ture of  the  germs  which  occasion  them. 

As  to  the  general  symptoms,  they  are  the  conse- 
quence of  the  absorption  of  the  toxic  substances 
elaborated  by  the  micro-organisms  at  the  wound  it- 
self. The  appearance  of  febrile  symptoms,  and  more 
especially  abnormal  elevation  of  temperature,  are  the 
first  indications  of  the  intoxication  ;  they  enable  the 
practitioner,  in  the  absence  of  any  other  evident 
cause,  to  assure  himself  of  the  infection  of  the  wound, 
and  they  constitute  an  important  indication  for  its 
subsequent  treatment.  Along  with  this,  poisoning 
of  the  nerve  centers  by  the  bacterial  ptomaines 
shows  itself  by  the  phenomena  of  coma,  stupor,  or 
even  delirium. 

The  blood  corpuscles,  in  contact  with  these  sub- 
stances, undergo  a  more  rapid  destruction,  and  their 
coloring  matter,  in  excess  in  the  plasma,  communi- 
cates to  the  interstitial  fluids,  and  notably  to  the 
visible  mucous  membranes,  a  dull  yellow  tint  more  or 
less  intense,  which,  in  severe  cases  indicates  the  ex- 
istence of  a  kind  of  hsemaphic  icterus ;  the  produc- 
tion of  this  last  condition  is  facilitated  by  the  circum- 
stance that  the  liver,  itself  altered,  is  unable  to 
eliminate  the  coloring  matter  which  the  blood  plasma 
carries  to  it  in  excessive  amount. 

The  germs  of  septicaemias  are  not  always  found  in 
the  blood;  some  of  them  are  anaerobic  and  unable  to 


Microbic  Diseases  Individually  Considered.      159 

multiply  there ;  in  the  case  of  others  they  may  be 
seen  to  penetrate  into  the  circulatory  fluids  when  the 
disease  is  of  rather  long  duration.  It  is  evident  that 
this  penetration  can  be  followed  by  new  troubles 
localized  in  the  different  parts  of  the  economy  in 
which  these  germs  become  arrested.  But  even  in  the 
absence  of  microbes  in  the  circulation,  general  symp- 
toms of  septicaemias  are  nearly  always  complicated 
with  local  symptoms  due  to  the  irritant  action  of  the 
absorbed  ptomaines.  Such  is  the  pathogeny  of 
parenchymatous  nephritis  with  albuminuria,  hepatitis, 
enteritis  with  diarrhoea,  pneumonia,  pleurisy,  peri- 
carditis, myocarditis,  endocarditis,  meningo-enceph- 
alitis,  etc.,  which  are  seen  to  develop  in  the  course 
of  septicaemias. 

Septicemic  fever  presents  several  varieties,  the 
clinical  importance  of  which  should  not  be  disre- 
garded. Traumatic  fever  is  the  mildest  form,  the  first 
degree  of  acute  septiccemia ;  the  latter  develops  in  sev- 
eral days  and  determines  a  greater  and  more  lasting 
elevation  of  temperature;  super-acute,  fulmiiiating,  or 
gangrenous  septiccemia  kills  the  subject  in  a  very  short 
time ;  finally,  chronic  septiccemia,  or  hectic  fever  occa- 
sions a  slow  pining  away  of  the  patient,  and  is  of 
much  longer  duration. 

Septicaemia  may  succeed  to  a  large  number  of  local 
lesions :  sanious  wounds,  abscesses,  erysipelas,  fu- 
runcle, gaseous  gangrene,  etc.  The  microbes  which 
occasion  it  are  very  variable  and  the  symptoms  are 
therefore  not  always  alike. 

The  pyogenic  germs  can  also  give  rise  to  a  pure 
septicaemia;  the  streptococcus  pyogenes  is  the  cause 
of    puerperal    fever;    the    staphylococcus    pyogenes 


160  Manual  of  Veterinary  Microbiology. 

aureus  has  been  met  with  in  the  blood  in  several 
cases  of  septicaemia.  In  such  cases  the  virulence  of 
these  germs  is  generally  very  great  and  death  super- 
venes too  quickly  to  allow  of  the  formation  of  pus. 
We  thus  see  puerperal  fever  under  three  different 
types  in  which  the  streptococcus  pyogenes  is  always 
found ;  it  sometimes  assumes  the  form  of  a  true  sep- 
ticaemia quickly  leading  to  death  ;  at  other  times  the 
patient  succumbs  with  an  abscess  of  the  large  liga- 
ments and  generalization  of  the  streptococcus,  with- 
out occasioning  new  abscesses;  finally,  the  disease 
sometimes  evolves  comparatively  slowly,  assuming 
the  characters  of  a  pyasmia  with  multiple  strepto- 
coccus abscesses. 

These  observations  show  that  in  septicaemia  and 
pyaemia  the  process  is  essentially  the  same ;  the  re- 
sult, in  case  of  pyaemia,  proceeds  from  the  special 
pyogenic  property  of  the  germ  and  from  its  par- 
ticular degree  of  virulence. 

The  lesions  found  at  autopsies  of  septicaemic  sub- 
jects are  far  from  being  constant.  However,  it  is  ob- 
served that  the  bodies  rapidly  putrefy.  The  paren- 
chyma of  the  liver,  kidney,  and  spleen  are  often  in- 
flamed and  softened.  We  may  also  find  inflammation 
of  the  various  serous  membranes:  pleura,  peri- 
toneum, pericardium,  endocardium,  etc.;  multiple 
hemorrhages  and  the  more  or  less  icteric  color  of 
all  the  tissues  indicate,  in  certain  cases,  profound 
alteration  of  the  blood. 

Pasteur's  septiccemia. 

We  will  not  delay  to  describe  the  history  of  the 
septicaemias  experimentally  obtained ;  they  present, 


Microbic  Diseases  Individually  Considered.       161 

indeed,  great  interest  from  a  general  bacteriological 
point  of  view,  but,  here,  we  will  only  study  those 
germs  which  the  veterinarian  is  liable  to  meet  with 
in  practice  and  which  it  is  absolutely  necessary  that 
he  should  be  acquainted  with. 

The  bacillus  septicus  or  septic  vibrio  takes  first  rank 
among  those  which  give  rise  to  the  most  character- 
istic phenomena  of  septicaemia.  It  is  the  cause  of  the 
complications  of  wounds  described  under  the  names 
of  gaseous  gangrene,  fulminating  gangrene,  traumatic 
gangrene,  and  malignant  oedema.  The  disease  which 
it  occasions  in  man  and  animals  has  been  desig- 
nated gangrenous  septiccemia  by  MM.  Chauveau  and 
Arloing. 

Characters  of  the  septic  vibrio. — It  is  a  rod  measuring 
4/1  in  length  by  Ip.  in  breadth,  hence  shorter  than 
that  of  bacteridian  charbon ;  it  is  often  jointed  like 
the  latter  but  its  difterent  segments 
have  not  all  the  same  length,  whilst 
the  articulated    segments   of   char- 
bon   are    of    uniform    dimensions. 
Further,  whilst  the  segmented  bac- 
teridia  are  cut  at  right  angles  and 
slightly  swollen  at  their  ends,  these 
characters  are  not  observed  in  the 

septic  bacillus.  According  to  Chau-      ^'  -'  ^-   ^^f^"^  «^ 

'■  1    A    1    •  1  •       T    Pasteur  s  septicgemia 

veau  and  Arloing,  when  examined  -^  ^^^    peritoneum 

in  the  oedema  of  a  septicsemic  focus,  and  in  the  blood. 

it  shows  itself:  Ist.  with  the  char-      4,  5.      Segmented 

acters  of  a  bacillis  (6«  to  50//  by  In  to  ^^^^'^^^ 

^   ^    .  1     ,       •  1  r-    J     '  6.     Bacillus     with 

1.5/^)  provided  with  a  spore  at  one  terminal  spore.-M. 
of   its  extremities,  which  is   occa-  and  L. 
24 


162  Manual  of  Veterinary  Microbiology. 

sionally  swollen ;  2d.  or  those  of  a  bacillus  with 
homogeneous  protoplasm,  a  little  longer  than  the 
preceding  (12/^  to  30//).  In  the  serous  membranes, 
and  in  the  blood  after  death,  it  grows  to  a  consider- 
able length  and  more  or  less  rapidly  becomes  seg- 
mented into  articles  of  varying  lengths,  never  sporu- 
lated  after  the  manner  of  the  bacillus  of  charbon. 

The  septic  vibrio  is  absolutely  anaerobic ;  it  exhibits 
very  active  flexuous  movements  which  are  quickly 
arrested  by  contact  with  oxygen. 

Action  of  physical  and  chemical  agents. — Heat  is  the 
surest  and  most  active  agent  of-  destruction  of  the 
septic  vibrio  and  the  only  one  to  be  recommended  in 
practice;  virulent  serosity  is  rendered  inoffensive  by 
heatmg  for  fifteen  minutes  at  100°;  dried  serosity  re- 
quires a  little  less  than  ten  minutes  at  120°.  It  slowly 
loses  its  virulence  through  the  influence  of  putrefac- 
tion (in  two  months) ;  the  virus,  dried  at  temperatures 
varying  from  15°  to  38°,  is  indefinitely  preserved. 
Antiseptics  have  a  feeble  toxic  power  for  the  septic 
vibrio;  according  to  MM,  Chauveau  and  Arloing  sul- 
phurous acid  has  shown  itself  the  most  powerful; 
sublimate,  at  1  to  500,  does  not  kill  the  bacillus  of 
gangrenous  septicismia.  Carbolic  acid,  at  three 
per  cent,  is  only  efficacious  when  supplemented  by 
heat. 

Cultures. — The  bacillus  septicus  multiplies  in  all 
the  artificial  media  under  the  express  condition  that 
these  media  and  the  atmosphere  in  which  they  are 
inclosed  are  deprived  of  oxygen.  The  development 
is  accompanied  with  the  disengagement  of  carbonic 
acid  and  hydrogen  ;  bouillons  become  turbid  and  then 
clear  by  the  deposition  of  the  bacilli ;  gelatin  is  fluid- 


Microbic  Diseases  Individually  Considered.      163 

ified.  Agar  is  well  adapted  to  its  culture  ;  on  this  me- 
dium it  forms  a  whitish  track  wath  festooned  borders 
and  extends  through  all  the  nutritive  mass  through 
the  breaking  up  of  the  latter  bv  the  liberated  gases. 
In  bouillon  the  bacilli  are  undulated  or  straight;  at 
first  homogeneous,  they  later  become  granular  and 
break  up.  Some  of  the  elements  become  sporulated; 
the  spore  most  frequently  appears  at  a  swollen  ex- 
tremity of  the  bacillus  and  gives  to  the  latter  the  ap- 
pearance of  a  bell  clapper.  When  cultivated  upon 
solid  media  the  bacilli  are  shorter,  and  fructification 
is  more  delayed. 

Inoculation  of  culture  media  should  be  made  either 
from  the  peritoneal  serosity  or  from  the  blood  of 
septicsemic  subjects.  But  as  the  blood  contains  very 
few  germs  immediately  after  death,  it  is  necessary, 
for  the  inoculation  to  be  successful,  to  allow  them  to 
multiply  there.  For  this  end  a  little  blood  is  inclosed 
in  a  pipette  and  kept  in  the  incubator  for  twenty-four 
hours ;  multiplication  of  the  bacilli  takes  place  and 
soon  shows  itself  by  the  appearance  of  bubbles  of 
gas.  The  blood  may  then  be  employed  for  the  in- 
oculation of  artificial  media.  Muscle  juice  can  be 
used  for  the  same  purpose. 

Research  and  coloration. — Examination  should  be 
made  of  the  serosity  of  the  oedema  or  of  the  septi- 
cseniic  focus,  of  the  blood,  peritoneal  serosity,  and 
muscle  juice.  By  studying  fresh  unstained  prepara- 
tions we  can  appreciate  the  movements  of  the  bacilli 
which  wind  among  the  elements  of  the  blood  or  se- 
rosity ;  it  will  be  noticed  that  the  rods  in  the  center  of 
the  preparation  preserve  their  motility  much  longer 


164  Manual  of  Veterinary  Microbiology.. 

than  those  in  the  vicinity  of  the  margin  of  the  cover 
glass  where  they  are  killed  by  contact  with  the  air. 

Experimental  inoculations. — The  species  endowed 
vvdth  receptivity  for  the  bacillus  of  gangrenous  sep- 
ticffimia  are  :  guinea  pig,  rabbit,  sheep,  goat,  horse;  then 
in  the  order  of  decreasing  affinity,  the  ass,  chicken, 
pigeon,  and,  finally,  the  dog  and  cat.  Cattle  are  abso- 
lutely refractory ;  this  is  a  remarkable  exception  which, 
itself,  is  sufficient  to  differentiate  this  pathogenic 
agent  from  that  of  sym[itomatic  charbon,  with  which 
is  has  several  points  of  resemblance. 

Inoculation  is  most  successful  when  made  in  the 
subcutaneous  cellular  tissue  (one-fifth  of  a  drop  to 
five  drops  of  the  virulent  serosity  are  sufficient) ;  it 
invariably  fails  when  made  with  the  lancet  or  by  su- 
perficial scarifications.  When  injected  into  the  cir- 
culation the  animal  can  tolerate  doses  much  larger 
than  those  which  prove  fatal  when  injected  into  the 
subcutaneous  cellular  tissue.  Subjects  inoculated  in 
this  way  suffer  from  a  fever  of  more  or  less  intensity 
and  obtain  immunity ;  but,  when  the  quantity  intro- 
duced into  the  blood  has  surpassed  one  to  three  drops 
of  the  virulent  serosity  in  the  rabbit,  one  to  five  cubic 
centimeters  in  the  sheep,  ten  to  thirty-five  cubic  centi- 
meters in  the  ass,  it  leads  to  the  death  of  the  inocu- 
lated subject.  In  animals  which  have  been  rendered 
refractory  by  intra-vascular  injection  later  inocula- 
tion in  the  connective  tissue  produces  a  slight  swell- 
ing or,  at  most,  the  formation  of  a  curable  abscess. 

The  serosity  taken  from  the  muscular  tissue,  the 
connective  tissue,  and  the  parenchymatous  oi'gans,  is 
more  virulent  than  that  from  the  serous  cavities. 

Inoculation  in  the  connective  tissue  is  followed  by 


Microhic  Diseases  Individually  Considered.      165 

a  violent  inflammatory  reaction  ;  the  region  becomes 
hot,  painful  and  tumefied ;  the  engorgement  rapidly 
extends  to  neighboring  regions  and  becomes  crepitant, 
emphysematous,  in  consequence  of  the  internal  forma- 
tion of  gas  (carbonic  acid,  hydrogen,  carburetted  and 
sulfuretted  hydrogen,  etc.).  Soon  the  central  part 
becomes  insensible  and  presents  all  the  symptoms  of 
mortification.  Gaseous  infiltration  may  be  wanting 
when  death  supervenes  too  quickly.  The  latter  ar- 
rives at  the  end  of  twelve  to  fifteen  hours  in  the 
guinea  pig.  The  autopsy  shows  great  detachment  of 
the  tissues,  their  infiltration  with  a  sanious  fluid  and 
fetid  gases,  gangrenous  patches  of  greater  or  less  ex- 
tent, and  often  great  extension  in  all  directions  of  the 
original  inflammation. 

Intra-vascular  inoculation  may  be  followed  by  the 
same  changes  when  a  solution  of  continuity  of  the 
circulatory  apparatus  allows  the  germs  to  penetrate 
into  the  connective  tissue  and  multiply  there,  shel- 
tered from  the  oxygen  of  the  blood. 

The  disease  is  transmissible  from  the  mother  to  the 
foetus. . 

Etiology  and  pathogeny. — The  septic  vibrio  is  almost 
every-where  present — in  the  soil,  the  dust  of  hay,  in 
most  putrid  substances  and  also  in  the  digestive  canal 
of  healthy  animals.  But  in  this  last  situation  it  is 
iuofiensive;  after  death,  however,  the  oxygen  be- 
coming deficient  in  the  tissues  which  during  life  op- 
pose themselves  to  its  penetration,  it  invades  these 
tissues,  multiplies  there,  and  in  this  way  we  are  able 
to  establish  its  presence  in  the  blood  (first  of  the 
portal  vein,  then  throughout  the  economy)  and  on 
the    surface    of    the   abdominal   viscera.      Similarly, 


166  Manual  of  Veterinary  Microbiology. 

when  it  accidentally  penetrates  into  the  living  tissues 
and  finds  there  good  conditions  of  vitalit}^  it  only 
multiplies  locally  and  not  iu  the  blood,  the  oxygen 
of  which  destroys  these  microbes  as  soon  as  they  en- 
ter this  medium;  on  the  contrary,  some  time  after 
death  it  is  found  in  the  circulatory  fluids. 

Large  wounds,  exposed  to  free  contact  with  the 
air,  are  not  easily  contaminated  on  account  of  the 
anaerobic  character  of  this  bacillus.  On  the  other 
hand,  the  latter  readily  implants  itself  in  irregular 
contused  wounds  where  the  affected  tissues  are  in 
way  of  necrosis.  The  following  experiment  of  MM. 
Chauveau  and  Arloing  is  decisive  in  this  regard.  If. 
after  the  injection  of  a  few  drops  of  the  virus  into 
the  jugular  of  a  ram,  the  circulation  is  arrested  in 
one  testicle  by  histournage,  this  testicle  becomes  the 
starting  point  of  a  fatal  gangrenous  process. 

When  a  wound  becomes  contaminated  with  the 
septic  bacillus,  if  the  local  conditions  are  not  adverse 
to  its  multiplication,  an  inflammatory  process  is  seen 
to  supervene  the  characters  of  which  are  those  of  the" 
experimental  oedema  noted  above.  Absorption  of 
the  products  elaborated  by  the  bacilli,  in  other  words, 
the  septic  intoxication,  leads  to  general  manifesta- 
tions of  the  disease  which,  sooner  or  later,  terminates 
fatally.  In  fact,  when  30  to  40  cub.  cent,  of  the  se- 
rosity  of  the  cedema,  deprived  of  its  bacteria  by  fil- 
tration, are  injected  into  the  guinea  pig,  it  leads  to 
death  in  a  few  hours  with  symptoms  of  septicaemia. 

Transmission  of  the  disease  from  one  subject  to 
another  most  frequently  occurs  by  means  of  surgical 
instruments  which  have  been  contaminated  by  con- 
tact with  an  infected  wound;  this  is  the  cause  of  the 


Microbic  Diseases  Individually  Considered.       167 

epidemics  which  have  been  observed  in  mankind  ; 
since  the  time  that  disinfectants  came  into  general  use 
this  complication   of  wounds  has   become  extremely 

rare. 

Septiccemias  of  the  rabbit. 

The  rabbit  is  very  sensitive  to  the  action  of  patho- 
genic microbes  ;  it  succumbs  in  a  comparatively  short 
time  to  inoculation  with  the  majority  of  these  germs, 
and  for  this  reason  constitutes  an  important  laboratory 
auxiliary.  The  experiments  of  Davaine,  Coze  and 
Feltz,  and  of  Koch  upon  the  virulence  of  putrid  ma- 
terial were  made  principally  with  this  rodent.  Of 
these  researches  we  have  only  to  refer  to  those  which 
relate  to  the  experimental  septiccemia  of  Koch  ;  the 
microbe  peculiar  to  this  disease  shows,  indeed,  many 
characters  in  common  with  those  of  certain  diseases 
of  our  animals,  such  as  chicken  cholera,  duck  cholera, 
pneumo-enteritis  of  the  pig,  and  the  epizootic  of  deer 
{wild-seuche).  But,  independent  of  all  experimental 
conditions,  rabbits  may  contract  diseases  of  a  similar 
nature,  which  prevail  epizootically  in  their  hutches 
and  occasion  serious  losses.  These,  in  contradis- 
tinction to  the  preceding,  are  designated  sponiaiieous 
septiccemias.  We  will  study  here,  in  their  essential 
points,  first,  the  experimental  septicaemia  of  Koch,  and 
then  the  spontaneous  septicaemias.  The  reader  will 
readily  notice  the  points  of  similarity  of  these  differ- 
ent diseases. 

Experimental  septiceemia  of  the  rabbit.     {Koch.) 

Koch  produced  this  disease  by  the  injection  of  a 
maceration  of  putrefied  meat ;  he  obtained  a  putrid 
phlegmon,  and   death   at  the  end  of  three  days  ;  the 


168  lianuat  of  Veterinary  Microbiology. 

oedematous  serosity  at  the  periphery  of  the  abscess, 
when  inocuhited  in  very  small  doses,  transmits  a 
septicaemia,  fatal  in  twenty-four  hours,  to  successive 
series  of  rabbits. 

The  oedematous  fluid  and  the  blood  contain,  in 
large  numbers,  ovoid  microbes  0-8//  to  Ijx  in  length, 
of  which  the  extremities  only  take  the  color,  so  that, 
after  staining,  it  affects  the  form  of  an  8. 

The  disease  is  easily  transmissible  by  inoculation  to 
all  species  of  birds  ;  according  to  Petri  it  may  even 
prevail  as  an  epizootic  in  chickens,  ducks  and  geese. 
It  is  not  transmitted  to  the  guinea  pig. 

In  the  rabbit  it  gives  rise  to  the  following  lesions: 
oedema  at  the  point  of  inoculation,  heiiiorrhagic 
patches  on  the  peritoneum  and  in  the  lung,  and  en- 
largement of  the  spleen.  Inoculated  birds  show  a 
rapid  emaciation  with  lowering  of  the  body  tem- 
perature; death,  preceded  by  convulsions,  arrives  in 
less  than  twenty-four  hours.  The  alterations  con- 
sist in  ecchymoses  in  the  cellular  tissue,  abdominal 
effusion,  petechise  upon  the  intestine,  infiltration  of 
the  lung,  and  the  presence  of  a  spumous  mucus  in 
the  bronchi.  The  blood  of  birds  transferred  again  to 
the  rabbit  in  the  smallest  traces,  reproduces  the  sep- 
ticaemia in  the  latter. 

Spontaneous  septiccBmias  of  the  rabbit. 
Lucet  has  described  a  disease  of  these  animals 
which  prevailed  in  the  hutches  and  occasioned  serious 
losses.  The  subjects  show  inappetence,  emaciation, 
torpor  and  temporary  muscular  spasms ;  diarrhoea 
also  occasionally  supervenes,  and  death  always  quickly 
ensues.     At  the  autopsy  the  blood  is  dark,  the  spleen 


Microbic  Diseases  Indlcidaally  Considered.       169 

much  enlarged  and  darkened ;  the  pleura  and  peri- 
toneum are  the  seat  of  exudative  infiamraation  with 
fibrinous  deposits,  and  tliere  is  slight  abdominal 
effusion. 

The  blood  and  organs  contain  a  non-motile  micro- 
coccus, isolated  or  associated  in  pairs,  0-7,«  to  0-9/z  in 
diameter;  it  takes  the  stain  quite  uniformly  through- 
out, but  is  not  stained  by  the  Gram  method.  It  is  at 
once  aerobic  and  anaerobic,  quickly  loses  its  virulence 
in  cultures  left  in  contact  with  the  air,  and  does  not 
vegetate  on  gelatin  or  potato. 

The  disease  is  transmissible  from  rabbit  to  rabbit, 
from  the  rabbit  to  the  guinea  pig  and  inversely,  by 
inoculation,  ingestion  and  by  simple  cohabitation. 
Its  virulence  becomes  attenuated  in  the  organism  of 
the  guinea  pig,  but  regains  its  original  strength  on  its 
return  to  the  rabbit.  In  this  last  a  culture  which, 
from  age,  has  lost  a  part  of  its  virulence  gives  at  first 
a  local  abscess.  The  disease  studied  by  Lucet  is  not 
transmissible  to  the  chicken.  The  food  and  dejec- 
tions are  the  vehicles  of  the  germ  and  it  is  by  their 
intermediation  that  the  natural  infection  occurs. 

Thoinot  and  Masselin  have  also  studied  a  spon- 
taneous septicaemia  of  the  rabbit  which  decimated 
the  hutches  at  the  Alfort  school.  The  symptoms 
noted  are  loss  of  appetite  and  vigor,  acceleration  of 
respiration,  and  sometimes  diarrhoea.  The  lesions 
consist  in  a  dark  color  of  the  blood,  deep  wine  color 
of  the  muscles,  roseate  or  yellow  eff'usion  of  the 
peritoneum  and  pleura,  and  albuminous  urine. 

The  disease  was  attributed  to  a  micrococcus,  single 
or  associated  in  pairs,  .motile,  presenting  in  birds  the 
appearance  of  a  short  bacillus  like  the  figure  8,  of 


170  Manual  of  Veterinary  Microbiology. 

which  the  two  extremities,  possessing  more  affinity 
for  the  coloring  matter,  are  separated  by  a  clear 
apace.  This  microbe,  once  colored,  is  decolorized  by 
the  methods  of  Gram  and  of  Weigert.  It  is  found  in 
large  numbers  in  the  blood  and  in  most  of  the  organs 
when  the  disease  has  lasted  for  some  time;  on  the 
contrary,  it  is  much  rarer  in  very  acute  forms. 

Its  culture  is  easy;  it  behaves  as  a  facultative 
anaerobe  and  reproduces  itself  in  the  form  of  a  mo- 
tile diplococcus  recalling  absolutely  the  microbe  of 
chicken  cholera.  After  twenty  days  exposure  to  the 
air,  its  cultures  in  bouillon  have  lost  all  virulence. 
When  growing  in  bouillon  the  latter  becomes  turbid, 
then  clear  again  ;  gelatin  is  not  fluidified  and  the  cul- 
ture in  this  medium  takes  the  form  of  a  thick,  white, 
glistening  track,  dentated  at  its  margin. 

The  disease  is  readily  transmitted  from  rabbit  to 
rabbit ;  it  is  also  inoculable  to  the  guinea  pig  and  to 
all  species  of  birds,  in  which  it  occasions  symptoms 
resembling  those  of  avian  cholera.  When  the  virus 
is  inoculated  in  the  pectoral  muscle  it  produces  a  se- 
questrum in  all  respects  comparable  to  that  caused 
by  the  inoculation  of  this  last  disease. 

Chicken  cholera.  {Fowl  cholera.) 
This  is  an  extremely  fatal  disease  which  prevails 
epizootically  among  farm-yard  fowls.  It  is  charac- 
terized by  easily  recognizable  symptoms :  the  affected 
animals  lose  their  accustomed  vigor,  generally  as- 
sume the  sitting  posture,  or  move  listlessly  around; 
they  are  chilly  and  seek  the  sunshine,  their  plumage 
is  ruffled,  giving  them  the  appearance  of  a  ball  of 
feathers;  the  comb  becomes  purple,  bluish,  or  even 


Microhic  Diseases  Individually  Considered.      171 

black.  The  appetite  soon  disappears ;  an  abundaut 
diarrhoea  ensues  with  expulsion  of  a  glairy  material 
and  occasionally  a  viscid  liquid  may  be  rejected  by 
the  beak.  Death  supervenes  in  a  few  days,  some- 
times preceded  by  convulsive  movements;  but  the 
disease  may  be  fulminating,  and  we  then  find  fowls 
dead  in  their  nests,  the  disease  having  produced  its 
effects  during  the  deposition  of  the  egg.  Cholera 
may  also  be  of  considerable  duration  and  give  rise  to  a 
slow  emaciation  of  the  affected  animals ;  in  these  cases, 
again,  death  is  the  usual  termination  of  the  disease. 

Fowl  cholera  is  the  cause  of  serious  losses,  hun- 
dreds of  poultry  sometimes  dying  in  the  same  yard 
within  a  few  weeks.  The  disease  appears  to  have 
not  always  the  same  degree  of  malignity ;  this  pe- 
culiarity is  accounted  for  by  the  great  mutability  of 
the  germ  which  occasions  it. 

The  changes  found  at  the  autopsy  are  quite  con- 
stant: the  blood  is  dark,  usually  tarry  in  aj^pearance; 
however,  it  is  not  uncommon  to  find  consistent  clots  in 
the  cavities  of  the  heart.  The  liver  is  large,  dark,  or 
sometimes  of  a  rather  light-brown  color,  and  dotted 
with  hemorrhagic  patches;  the  intestines  contain  a 
quivering  jelly-like  mucus  more  or  less  adherent  to 
the  mucosa;  the  latter  is  inflamed,  sometimes  ulcer- 
ated, its  alterations  being  more  marked  as  the  disease 
has  been  of  longer  duration  ;  in  acute  cases  we  es- 
pecially notice  in  this  situation  the  presence  of  nu- 
merous petechise.  The  heart  shows  a  characteristic 
lesion  :  its  external  surface  is  dotted  with  hemorrhagic 
points  localized  especially  in  the  coronary  groove  ;  the 
pericardial  sac  contains  a  quantity  of  fluid  exudate 
and  a  gelatinous  deposit  adherent  to  the  heart ;  this 


172  Manual  of  Veterinary  Microbiology. 

deposit  is  rarely  absent.     Miliary  extravasations  may 
also  be  found  in  the  nerve  centers. 

Fig.  4.  Microbe.  —The  blood,  the  dejections 

and  the  pericardial  exudate  contain, 
„  ,     *  ^       in  large  numbers,  a  micro-organism, 
-    J     *        very  short  and  ovoid,  resembling  in 
shape  the  figure  8.     It  is  a  diplo-bac- 
i,  ^  terium,  the  extremities  of  which  are 

"  less  refringent  and  have  more  affinity 

1.  Microbes  of  for  the  coloring  matters  than  the  mid- 
chicken  cholera  die  part,  which  remains  clear.  It 
in  figure  8  form;  q^^q^  appears  as  a  micrococcus ;  this 
2.    The    same    in  ,        ,       ^ . ,     ,  .  i         .  , 

their  real  form—  -"^  When  its  long  axis  corresponds  with 

bacilli  with  clear  the  direction  of  the  visual  ray  and  the 
central  space.  (M.  organism  is  seen  on  one  of  its  ends, 
and  L.)  j^  -g  jjiotile,  its  movements  being  very 

rapid  in  preparations  of  fresh  blood.*  It  measures 
from  0-6/i  to  0-8//  in  length  by  0-3/^  to  0-4/^  in  thick- 
ness. It  is  a  facultative  aerobe,  oxygen,  however,  be- 
ing favorable  to  its  multiplication. 

Action  of  physical  and  chemical  agents. — The  bac- 
teria of  chicken  cholera  are  killed  in  fifteen  minutes 
at  50°,  in  ten  minutes  at  80°,  still  more  quickly  at  boil- 
ing temperature.  By  desiccation  they  are  killed  in 
a  few  daj^s.  Corrosive  sublimate,  at  1  to  5,000,  kills 
them  in  one  minute,  carbolic  acid,  at  three  per  cent,  in 
six  hours.  They  are  not  affected  by  the  gastric  juice. 
By  the  oxygen  of  the  air  they  are  first  attenuated 
and  then  killed. 

Cultures. — This  germ  grows  well  in  bouillon  in  the 
presence    of  air ;    during   its   growth   this    medium 

*  [Described  in  German  works  as  non-motile.^D.J 


Microbie  Diseases  Individually  Considered.      178 

quickly  becomes  clouded  and  at  the  end  of  several 
days  clears  again  by  tlie  deposition  of  tlie  micro- 
organisms. 

Gelatin  inoculated  in  lines  becomes  covered  along 
the  latter  by  a  raised  transparent  pellicle;  inoculated 
by  puncture  it  shows  small  gray  colonies  all  along 
the  needle  track;  it  is  not  fluidified. 

The  culture  succeeds  very  indifferently  on  potato. 

Research  and  coloration. — The  microbes  of  chicken 
cholera  are  easily  distinguished,  under  strong  mag- 
nification, in  uneolored  preparations  of  fresh  blood; 
they  appear  as  very  refringent,  mobile  diplo-cocci. 
They  must  be  stained  with  the  hydro-alcoholic  solu- 
tions as  they  are  decolorized  by  the  Gram  method; 
Lofiler's  method  is  most  suitable,  especially  when  it 
is  desired  to  study  the  microbes  in  sections. 

Exjperimental  inoculations. — The  disease  prevails 
spontaneously  in  and  is  successfully  inoculated  to  all 
species  of  poultry:  chickens,  ducks,  geese,  pigeons, 
and  turkeys;  the  pheasant  and  sparrow  are  also  sus- 
ceptible. Subcutaneous  inoculation  and  ingestion 
give  results  almost  equally  certain.  The  introduc- 
tion of  the  virulent  matter  into  the  pectoral  muscle, 
by  means  of  the  Pravaz  syringe,  causes  the  formation 
of  a  sequestrum  which  is  the  more  pronounced  as 
the  experimental  disease  is  of  longer  duration.  This 
sequestrum,  however,  is  not  characteristic  of  the  dis- 
ease ;  it  may  be  seen  after  the  injection  of  other  germs 
(those  of  pneumo-enteritis  of  the  pig,  the  spontane- 
ous rabbit  septicsemia  of  Thoinot  and  Masseliu,  and 
a  number  of  septic  bacteria). 

The  rabbit  is  extremely  sensitive  to  chicken  chol- 
era.    The  subcutaneous  injection  of  a  drop  of  blood 


174  Manual  of  Veterinary  Microbiology. 

coming  from  a  diseased  chicken  kills  it  in  twenty- 
four  hours.  Hence,  it  is  a  delicate  reagent  for  veri- 
fying the  nature  of  an  epizootic  of  fowl  cholera,  but, 
in  order  that  this  experiment  should  be  of  real  value, 
it  is  evidently  necessary  to  carefully  avoid  all  causes 
of  error  which  may  result  from  the  intervention  of 
foreign  germs.  The  blood  of  the  rabbit  which  suc- 
cumbs under  such  conditions  is  exceedingly  rich  in 
the  specific  germs.  The  rabbit  can  also  be  infected 
by  way  of  the  digestive  canal. 

Inoculation  of  a  drop  of  blood  from  a  diseased 
chicken  in  the  subcutaneous  cellular  tissue  of  the 
guinea  pig  causes  an  abscess  which  heals  by  evacua- 
tion of  the  pus ;  but  inoculation  into  the  blood  results 
in  death,  the  same  as  in  the  rabbit  and  chicken,  by 
blood  asphyxia.  The  pus  of  the  abscess,  in  the 
guinea  pig,  is  rich  in  microbes  and  its  inoculation  to 
chickens  or  to  the  rabbit  reproduces  the  disease. 

It  appears  from  a  number  of  observations  that  the 
contact  of  virulent  blood  or  of  a  culture  with  a 
wound  can  occasion  in  man,  also,  the  formation  of  an 
abscess,  and  that  the  cat  and  the  dog  may  consume, 
with  impunity,  chickens  which  have  died  from  the 
disease. 

Etiology  and  pathogeny. — The  germ  of  chicken  chol- 
era is  deposited  on  the  soil  of  poultry  houses  and 
yards  with  the  fluid  dejections  of  diseased  fowls; 
their  entrance  into  the  organism  of  healthy  subjects 
takes  place  by  way  of  the  digestive  canal,  the  fowls 
taking  up  particles  contaminated  with  the  germs 
along  with  their  food.  The  transmission  of  the  dis- 
ease by  ingestion  has,  moreover,  been  experimentally 
proved.     Since  desiccation  and  contact  with  the  air 


Microhic  Diseases  Individually  Considered.      175 

quickly  kills  the  microbe,  it  is  in  moist  poultry  pens, 
in  which  the  excretions  accumulate,  and  in  stagnant 
waters  of  the  yards,  that  the  virus  is,  for  the  most 
part,  preserved.  The  germs  of  the  disease  may  thus 
persist  for  a  long  time  on  one  farm  even  after  the  re- 
moval of  all  diseased  fowls. 

The  microbe  of  chickeii  cholera,  being  aerobic,  ex- 
tracts the  oxygen  from  the  blood  and  thus  determines 
symptoms  of  asphyxia,  which  show  themselves  by 
the  dark  blue  color  of  the  comb,  general  coolness  of 
the  body,  and  hemorrhagic  patches  on  the  pericar- 
dium, liver,  peritoneum,  etc.  By  filtering  a  bouillon 
culture  through  plaster  of  Paris,  M.  Pasteur  has  ob- 
tained a  liquid  free  from  germs  and  which,  inoculated 
to  fowls,  produces,  temporarily,  the  most  prominent 
symptoms  of  the  disease,  giving  rise  to  a  condition 
similar  to  that  which  succeeds  to  the  absorption  of  a 
narcotic  dose  of  opium.  The  animal  is  at  first  ex- 
cited, then  its  feathers  become  rufiled,  the  appetite  is 
lost,  it  becomes  somnolent,  and,  after  several  hours, 
emerges  from  its  temporary  stupor.  Thus  we  see 
produced  experimentally  the  intoxication  w^hich  suc- 
ceeds to  the  multiplication  of  the  specific  bacteria  in 
the  blood. 

Attenuation — Preventive  inoculation. — In  cultivatinsr 
the  microbe  of  fowl  cholera  in  the  air  and  inoculatinsr 
cultures  of  difierent  ages,  M.  Pasteur  observed  that 
their  virulence  progressively  diminished.  Thus,  by 
inoculating  each  time  the  same  number  of  fowls  with 
virus  fifteen  days  old,  one  month,  two  mouths  and 
over,  he  observed  that  the  mortality  induced  by  these 
diiferent  specimens  of  virus  gradually  decreased,  and 
that,  at  a  certain  time,  all  the  inoculated  fowls  sur- 


176  Manual  of  Veterinary  Microbiology. 

vived.  If  at  the  time  that  a  fowl  is  inoculated  with 
a  virus  of  a  certain  degree  of  virulence,  this  same 
virus  is  inoculated  to  culture  media,  it  there  repro- 
duces itself,  communicating  to  its  progeny  the  special 
pathogenic  activity  which  it  itself  possessed;  the  at- 
tenuation of  the  germ  is  therefore,  in  this  case,  hered- 
itary. A  series  of  cultures  of  progressively  decreas- 
ing virulence  can  thus  be  prepared. 

The  attenuation  is  connected  with  the  action  of  the 
ox3'gen  of  the  air;  in  order  to  preserve  the  virulence 
of  cultures  it  suffices  to  exclude  them  from  contact 
with  the  air;  in  contact  with  the  latter  they  gener- 
ally become  inoffensive  at  the  end  of  two  months. 

The  attenuated  virulence  shows  a  series  of  degrees, 
from  the  normal  virulence  up  to  non-virulence. 
When  the  virus  is  enfeebled  to  such  an  extent  that  it 
no  more  kills  chickens,  it  develops  at  the  point  of  in- 
oculation in  the  pectoral  muscle  a  local  alteration, 
ending  in  the  formation  of  a  sequestrum  which  may 
either  be  eliminated  or  absorbed.  Fowls,  after  recov- 
ery, are  vaccinated  against  the  later  action  of  a  more 
virulent  or  mortal  virus.  The  immunity  thus  con- 
ferred is  the  more  efficacious  the  more  intense  the 
vaccinal  disease;  its  duration  appears  not  to  exceed 
one  year;  the  immunity  from  a  first  vaccination  is 
strengthened  by  inoculation  of  a  second  more  virulent 
vaccine.* 

The  enfeebled  virus  can  regain  its  virulence  when 

*  [Kitt  has  obtained  immunity  in  chickens  against  the  virus  of 
chicken  cholera  by  injection  of  the  blood  serum  of  previously  im- 
munised chickens,  as  well  as  by  injection  of  the  albumen  of  the 
e^gs  coming  from  immune   hens.     (Centralbl.  f.  Bad.  XIV,  25. j 
-D.] 


V        •  XI  XV.' 

Mlcrobic  Diseases  Individually  Considered.      177 

it  is  passed  in  succession  through  small  birds  (cana- 
ries, etc.). 

Infectious  enteritis  of  chickens. 

Under  the  name  of  infectious  enteritis,  Klein  has 
described  an  epizootic  disease  of  chickens  which  has 
much  resemblance  to  cholera;  the  initial  symptom  is 
diarrhoea;  the  subjects  are  quiet  but  never  show  the 
somnolence  so  characteristic  of  cholera.  Death  oc- 
curs in  twenty-four  to  thirty-six  hours  after  the  first 
manifestations  of  the  disease. 

The  intestinal  contents,  the  blood  and  the  splenic 
tissue  contain  a  special  bacillus  measuring  0-8//  to 
1*6//  in  length  by  0'3/i  to  0'4/i  in  thickness.  The 
chickens  naturally  become  infected  by  ingestion 
of  contaminated  substances.  Inoculation  of  the  blood 
of  a  diseased  chicken  into  the  subcutaneous  tissue  of 
another,  results  in  the  death  of  the  latter;  but  the 
inoculated  animal  remains  well  during  the  first  five 
days  and  dies  on  the  seventh  to  the  ninth,  whilst 
chickens  similarly  inoculated  with  fowl  cholera  suc- 
cumb in  twenty-four  to  thirty-six  hours.  Finally, 
the  bacillus  of  the  disease  described  by  Klein  appears 
not  to  be  pathogenic  for  the  rabbit  or  pigeon,  thus 
differing  from  that  of  cholera. 

Epizootic  dysentery  of  chickens  and  ducks. 

M.  Lucet,  veterinarian  at  Courtenay,  has  studied 
another  epizootic  disease  of  domestic  fowls,  which  he 
has  named  epizootic  dysentery  of  chickens  and  ducks;  a 
summer  disease  as  deadly  as  the  two  preceding,  this 
dysentery  especially  attacks  young  chickens  of  the 
same  year,  and  gives  rise  to  symptoms  which  strongly 
recall  those  of  cholera :  somnolence,  lassitude,  inap- 


178  3Ianual  of  Veterinary  Microbiology. 

petence,  diarrhoea,  chilliness,  ruffling  of  the  plumage, 
etc.  The  temperature,  at  first  high,  afterward  de- 
scends one  to  two  degrees  below  the  normal  figure  ; 
the  aniaial  dies  on  the  ninth  to  the  thirteenth  day  after 
the  beginning  of  the  disease,  occasionally  much  later. 

The  bacteria,  which  are  present  in  most  of  the 
lesions  and  especially  in  the  intestine,  show  them- 
selves in  the  form  of  short  bacilli  1-2/i  to  1*8//  in 
length,  occasionally  isolated,  more  frequently  united 
in  pairs,  motile,  at  once  aerobic  and  anaerobic,  rap- 
idly becoming  attenuated  in  cultures. 

The  disease  is  communicated,  by  ingestion  of  viru- 
lent products,  from  chicken  to  duck,  and  inversely. 
Inoculation  of  cultures  also  causes  it  in  the  same  fowls; 
but  ingestion  of  cultures  only  produces  the  disease 
when  the  diet  is  changed  at  the  same  time.  The 
pigeon  and  the  guinea  pig  are  refractory ;  the  rabbit 
takes  the  disease  only  by  intravenous  inoculation; 
subcutaneous  injection  remains  without  effect. 

Duck  cholera. 

Ducks  are  liable  to  contract  chicken  cholera  ;  in  ad- 
dition, they  may  be  attacked  by  another  contagious 
disease  which  is  also  characterized  by  diarrhoea, 
emaciation  of  the  affected  subjects,  and  by  its  usually 
fatal  termination;  it  has  been  described  under  the 
name  of  duck  cholera. 

This  disease  is  caused  by  the  multiplication  in  the 
blood  of  a  bacterium  presenting  the  greatest  mor- 
phological analogies  with  that  of  chicken  cholera;  it 
is  oblong,  short,  and  appears  bi-lobed  in  stained 
preparations  on  account  of  the  greater  affinity  of  its 
extremities  for  the  coloring  matters.     The  microbes 


Microbic  Diseases  Individually  Considered.       179 

of  duck  cholera  are  a  little  larger  than  those  of 
chicken  cholera.  Like  the  latter  they  do  not  admit 
of  double  staining. 

Their  culture  on  the  different  solid  media  is  richer 
than  that  of  chicken  cholera.  This  peculiarity  is  es- 
pecially noticeable  upon  potato,  which  is  a  very  bad 
field  for  the  growth  of  the  organism  of  chicken 
cholera,  whilst  that  of  duck  cholera  grows  very  well 
on  this  medium. 

Whilst  chicken  cholera  is  pathogenic  for  ducks, 
duck  cholera  is  inoffensive  for  chickens  and  pigeons. 
The  latter  disease  does  not  even  kill  all  ducks  with 
the  same  rapidity  ;  some  species  resist  for  a  longer 
time  than  others. 

The  rabbit  succumbs  to  duck  cholera  as  well  as  to 
chicken  cholera,  but  requires  a  larger  dose  of  the 
former  than  of  the  latter. 

It  might  be  thought  that  the  virus  of  duck  cholera 
was  an  attenuated  form  of  that  of  chicken  cholera. 
But  inoculation  of  the  former  to  the  chicken  ought 
then  to  vaccinate  against  the  latter  disease,  which  is 
not  the  case. 

The  penetration  of  the  germs,  in  the  case  of  spon- 
taneous contamination,  takes  place  by  the  digestive 
canal ;  this  mode  of  infection  has  also  been  demon- 
strated experimentally.  The  experimental  disease 
can  also  be  communicated  by  hypodermic  injection.* 

*  [Several  other  microbic  diseases  of  fowls  have  been  described : 
Vibrio-cholera  of  chickens  ( Vibrio  MeUchnikovi,  Gameleia)  in 
Russia, — caused  by  an  organism  presenting  morphological  and 
cultural  resemblances  with  that  of  Asiatic  cholera ;  septicaemia 
in  geese  {Spirochete  anserina,  Sakharoff)  in  swampy  regions  of 
Transcaucasia — a  spiral  microbe  resembling  that  of  relapsing  fever 


180  Manual  of  Veterinary  Microbiology. 

Bacteridian  charbon. 

This  is  an  infectious  and  contagious  disease  caused 
by  the  bacteridium.* 

The  disease  shows  itself  by  a  profound  adynamic 
fever,  with  more  or  less  marked  stupor  of  the  affected 
animals.  The  blood  is  much  changed,  viscid,  and  the 
plasma,  loaded  with  the  coloring  matter  of  the  cor- 
puscles, communicates  to  the  mucous  membranes  a 
dull  yellow  tint ;  sometimes  visible  hemorrrhages  oc- 
cur :  nasal  and  conjunctival  petechise,  bleeding  from 
the  lungs  and  bowels,  hematuria.  The  intesti- 
nal lesions  in  the  horse  often  give  rise  to  more  or  less 
violent  symptoms  of  colic,  and  this  complication, 
considered  too  exclusively,  frequently  interferes  with 
the  diagnosis  of  the  essential  disease. 

At  the  autopsy  the  blood  is  found  to  be  deoxygen- 
ated,  viscid,  incoagulated,  the  corpuscles  are  altered, 
agglutinated,  and  the  plasma  colored  red.  The  inter- 
nal tunic  of  the  bloodvessels  and  of  the  heart  is  also 
often  stained  red;  petechise  are  found  on  the  heart, 
lung,  pleura,  and  peritoneum.  The  spleen  is  much 
enlarged  ;  its  borders,  clear  cut  in  the  normal  condi- 
tion, have  become  rounded  ;  its  surface  is  often  lumpj^ 
its  consistence  soft  and  friable,  and  its  meshes  infil- 
trated with  extravasated  blood.     The  intestines  are 

of  man  is  found  in  the  blood,  not  cultivated ;  epizootic  disease 
of  grouse  (Klein)  in  England  ;  epizootic  pneumo-pericarditis  in 
turkeys  (McFadyean)  in  England. — D.J 

*  [The  term  "  Bacteridium  "  or  "  la  bacteridie,"  derived  from  the 
genus  Bacteridium  of  Davaine's  early  classification  is  retained  by 
French  writers  as  a  specific  name  for  the  bacillus  anthracis.  "  Bac- 
teridian charbon"  or  "  charbon,"  refers  to  the  disease  produced 
by  this  organism.  Synonyms:  anthrax,  splenic  apoplexy,  etc. — 
Ger.  Milzbrand.— D.J 


3Iicrobic  Diseases  Induidualhj  Considered.      181 

sometimes  the  seat  of  intense  congestive  and  hemor- 
rba^^ic  lesions,  and  in  some  cases  the  lymphatic  glands 
of  the  different  resfions  are  in  the  same  condition,  and 
also  enlarged  to  twice  or  three  times  their  normal 
size.  Similar  lesions  may  also  be  found  in  the  kid- 
neys, meninges,  etc. 

The  species  which  are  liable  to  contract  the  spon- 
taneous disease  are  the  sheep,  goat,  ox,  and  horse;  this 
last  less  readily  becomes  infected  than  the  first ;  it  can 
consume  with  impunity  foods  which  occasion  the  dis- 
ease in  the  others.  Charbon  is  also  met  with  in  the 
carnivora  of  menageries  (lion)  when  they  are  fed  with 
the  flesh  of  animals  which  have  died  of  this  disease. 
Exceptionally  the  dog  and  the  jpig  become  infected  in 
the  same  way.  Algerian  sheep  are  refractory  even 
when  they  are  born  in  other  countries. 

Man  is  unfortunately  also  liable  to  contract  this 
disease;  the  latter  then  receives  different  names  ac- 
cording to  the  mode  of  penetration  of  the  bacteridiiim 
and  the  initial  lesion  which  it  determines : 

1st.  Malignant  pustule,  the  most  frequent  form,  con- 
secutive to  the  accidental  insertion  of  the  virus  into  a 
cutaneous  wound,  develops  in  workmen  who  cut  up, 
dress,  or  retail  charbonous  meat. 

2d.  Pulmonary  charbon,  the  rarest  form,  develops  in 
consequence  of  the  inhalation  of  dust  charged  with 
the  bacteridia,  or  rather  with  their  spores,  in  work- 
men who  handle  wool  or  skins  comins:  from  the  bod- 
ies  of  charbonous  subjects. 

3d.  Intestinal  charbon,  consecutive  to  the  consump- 
tion of  charbonous  meat. 

Characters  of  the  bacteridium. — The  microbes  of 
charbon  are  straight,  cylindrical  rods;  they  are  iso- 


182  Manual  of  Veterinary  Microbiology. 

lated  or  associated  in  twos  or  threes,  rarely  more, 
the  limits  of  the  articles  being  then  marked  by  one  or 
more  articulations  or  clear  zones  distinctly  travers- 
ing the  polybacillar  filament ;  often  two  contiguous 
elements  have  commenced  to  detach  themselves  and 
form  between  them  a  large  open  angle  with  the  articu- 
lation partly  disconnected,  forming  its  apex. 

The  different  segments  of  the  same  filament  are  of 
equal  length  ;  each  segment  is  very  slightly  swollen 
at  its  extremities.  Their  dimensions  vary  from  5//  to 
10/i  iu  length  by  1//  to  1-5/z  in  thickness.  The  com- 
pound filaments  are  never  of  great  length  in  the 
blood  of  animals  dead  of  charbon  on  account  of  their 
constant  collision  with  the  blood  corpuscles.  In  arti- 
ficial cultures,  on  the  contrary,  they  become  consider- 
ably elongated,  important  changes  at  the  same  time 
being  seen  to  take  place  in  their  substance;  their 
Fig  5.  homogeneous    contents   become 

I         .         ■         modified,  condensing  in  the  form 
'  ■         i^       l'        of  spores ;  the  latter  are  ovoid  cor- 
^1         puscles,  highly  refringent,  less  thick 
'  than  the  filament  itself  and  conse- 

quently never  produce  bulgings  in 
the  latter.     The  formation  of  the 
spores  is  followed  more  or  less 
1  2, 3    Charbon  ba-     ^  ].|    ^    ^^3^^  liberation,  through 
cilli  m  the  blood.  \       ^.  \     "^  .  ^   ,       ,., 

4.  The  same  in  a  cul-  the  disintegration  ot  the  filaments. 

ture,  sporulated.  (M.  Reproduction  of  the  bacteridium, 
^^^  L-)  therefore,  takes  place  only  by  fis- 

sion in  the  bodies  of  diseased  animals  during  life;  in 
cultures  the  transversal  division,  only  brought  into 
view  by  staining,  is  followed  by  sporulation,  but  only 
between  certain  limits  of  temperature  ;  it  begins  above 


Microbic  Diseases  Individually  Considered.       183 

12°  and  ceases  at  40°,  and  is  the  more  active  in  pro- 
portion as  the  nutritive  fluid  becomes  more  exhausted. 

The  bacilhis  of  charbon  is  non-motile  and  aerobic ; 
the  presence  of  oxygen  is,  indeed,  absolutely  neces- 
sary for  sporulation. 

Action  of  physical  and  chemical  agents. — A  tempera- 
ture of  45°  arrests  the  vegetation  of  the  charbon 
bacilli ;  at  42-5°  they  multiply  only  by  fission,  no 
longer  giving  birth  to  spores,  and  they  also  become 
attenuated. 

The  rods  are  killed  by  several  minutes  exposure  to 
a  temperature  of  50°  ;  the  spores,  however,  are  not 
influenced  by  this  temperature  ;  in  the  moist  con- 
dition they  resist  80°  and  when  dry  support  with  im- 
punity a  temperature  of  100°. 

The  bacteridia,  in  the  condition  of  mycelium,  that 
is,  the  rods,  are  destroyed  by  putrefaction ;  hence 
they  quickly  disappear  from  carcasses  abandoned  to 
the  air.  But  this  is  not  the  case  for  those  in  which 
the  viscera  have  been  immediately  removed,  and  more 
especially  for  bodies  of  charbonous  animals  which 
have  been  bled  and  dressed.  Putrefaction,  in  this  par- 
ticular case,  is  much  more  tardy,  and  it  is  possible 
to  find  the  charbon  bacillus  in  the  blood  several  days 
after  death.  This  is  a  fact  of  very  great  practical 
importance  and  one  which  meat  inspectors  ought 
carefully  to  notice. 

It  would  seem  that,  the  bacilli  of  charbon  being 
destroyed  by  the  putrefaction  of  the  cadavers,  the 
latter  would  not  constitute  a  source  of  danger  for 
later  contaminations.  But  after  the  death  of  the  dis- 
eased animals  all  the  bacilli  are  not  destroyed;  those 
which  come  into  contact  with  the  external  air  form 


184:  Manual  of  Veterinary  Microbiology. 

spores  and  these  are  completely  resistant  to  decora- 
position.  In  bodies  from  which  the  skin  has  been  re- 
moved the  exposure  of  a  large  number  of  bacilli  in- 
volves a  more  abundant  production  of  spores  than  in 
those  which  have  not  been  skinned. 

The  bacilli  accidentally  deposited  upon  the  soil  by 
diseased  animals,  finding  themselves  in  contact  with 
the  air  and  at  a  suitable  temperature  will  also  form 
spores,  which  are  preserved  for  a  long  time  on  the 
surface  of  the  vegetation.  According  to  some  au- 
thors, these  spores  themselves  can  pass  through  the 
different  phases  of  their  evolution  in  the  soil  and 
give  rise  to  new  generations. 

The  bacteridia  retain  their  virulence  for  a  length- 
ened period  in  the  blood  when  this  liquid  has  been  care- 
fully collected  and  protected  from  the  invasion  of  the 
germs  of  decomposition.  Dried  blood  also  long  re- 
tains its  virulence;  the  bacilli  are  brought  to  the  con- 
dition of  latent  life  and  will  again  multiply  when  un- 
der good  conditions  of  humidity  and  temperature. 

Antiseptics  act  very  differently  on  the  bacilli  and 
on  their  spores.  Thus  one-fourth  to  one-half  per 
cent  solution  of  carbolic  acid  kills  the  rods,  whilst  a 
five  per  cent  solution  is  required  to  kill  the  spores. 
The  bacteridia  are  killed  by  carbonic  acid,  by  com- 
pressed oxygen,  and  by  absolute  alcohol,  whilst  the 
spores  resist  these  agents. 

Cultures. — The  bacilli  of  charbon  readily  multiply 
in  artificial  media  at  temperatures  between  12°  and 
43°,  and  in  contact  with  the  air.  The  most  favorable 
temperature  is  about  38°. 

In  bouillon^  after  the  first  day,  white  mucoid  flakes 
are  seen  suspended  in  the  fluid;  these  do  not  become 


Microbic  Diseases  Individually  Considered.       185 

dissociated  by  shaking.  They  slowly  increase  in  size, 
still  remaining  united;  they  are  formed  of  filaments 
of  great  length  intwined  with  each  other  like  the 
threads  of  cotton  wadding.  After  a  certain  time 
these  filaments  produce  spores  and  break  up ;  the  lib- 
erated spores  fall  to  the  bottom  of  the  vessel  where 
they  look  like  fine  sand. 

Inoculated  to  gelatin  by  puncture,  the  charbon  bacillus 
forms  a  culture  no  less  characteristic;  along  the  deep 
track  a  white  line  appears  from  which  project  hori- 
zontally ramifying  branches,  so  that  the  whole  simu- 
lates the  branch  of  a  tree  with  its  divisions  and  sub- 
divisions ;  on  the  surface  a  white  layer  is  formed 
which  slowly  fluidifies  the  gelatin  and  gradually  in- 
creases in  thickness. 

The  colonies  which  develop  on  gelatin  plates  are 
formed  of  tufts  of  interlacing  filaments  showing  ar- 
borescent prolongations  at  their  periphery. 

On  agar  the  bacteridium  grows  as  upon  gelatin.* 

On  potato  it  produces  a  dry  crust  of  a  white  color. 

Virulent  cultures  contain  various  toxic  substances: 
a  toxalbuminoid,  precipitated  by  alcohol  (Nankin, 
J3rieger,  Fraenkel),  and  an  alkaloid  (Martin). 

Research  and  coloration. — The  charbon  bacillus  is 
found  in  the  blood  of  animals  which  have  died  from 
the  disease,  and  in  the  local  oedema  consecutive  to  ac- 
cidental or  experimental  inoculation.  It  is  easily 
recognized  in  fresh  unstained  blood  preparations  in 
the  form  of  very  clear  articulated  or  non-articulated 
rods,  lying  motionless   between   the   corpuscles.      It 

*  [But  the  growth  in  agar  tubes  is  in  no  way  characteristic. — D.] 

16 


186 


Manual  of  Veterinary  Microbiology. 


Fig.  6. 


readily  takes  the  difierent  aniline  stains ;  the  blood 
may  be  stained  with  aqueous  solutions  either  directly 

or  after  being  dried 
on  the  cover  glass ; 
in  this  last  case  the 
bacteridia  are  gene- 

V  '^fcaS™*    ^       B  rally     shorter     and 

^^^M^^*.^^  %^    ^^        more    slender.     The 

double  stains  of 
Gram  and  Weigert 
give  excellent  re- 
sults.* 

Examination  of 
fresh  blood  is  espe- 
cially to  be  recom- 
mended here,  as  it 
enables  us  to  estab- 
lish the  immobility 
of  the  bacilli  and  the 
alterations  of  the  blood  corpuscles.  In  examining 
the  blood  of  a  carcass  for  bacteridia  the  specimen 
must  be  taken  from  a  deep  vein  some  distance  from 
the  peritoneum,  because,  in  this  disease,  the  invasion 
of  microbes  coming  from  the  abdominal  viscera  is 
more  rapid  as  the  charbon  bacillus,  being  aerobic,  has 
deprived  the  blood  of  its  oxygen. 

Experimental    inoculations.  —  Inoculation^   may   be 
made   by    subcutaneous    injection,   by   intra-vascular 

*  [The  Gram  stain  is  especially  applicable  to  the  staining  of  sec- 
tions. On  cover-glass  preparations  the  characteristic  appearance 
of  the  bacillus  is  best  brought  out  by  the  use  of  aqueous  or  hydro- 
alcoholic  solutions.  Loffler's  stain,  followed  or  preceded  by  eosin, 
gives  excellent  results. — D.] 


Anthrax  bacilli  in  the  blood. 
( Cover-glass  preparation ) . — Kitt. 


Microhic  Diseases  Individually  Considered.       187 

injection,  or,  more  simply,  by  superficial  scarifications 
of  the  integument.  The  disease  can  also  be  artifi- 
cially communicated  by  ingestion,  or  even  by  inhala- 
tion. To  confirm  a  diagnosis  hypodermic  inoculation 
and  scarifications  are  amply  sufiicient. 

The  substances  to  be  inoculated  are  represented  by 
the  blood  or  its  serum  and  the  diluted  pulp  of  organs 
rich  in  vessels :  spleen,  liver,  lymphatic  glands,  etc.; 
in  laboratories  cultures  are  also  used  for  inoculation. 

The  disease  is  transmissible  by  inoculation  to  nearly 
all  the  domesticated  animals.  Mice,  guinea  pigs,  and 
rabbits  are  the  animals  which  are  most  frequently 
employed  for  experimental  inoculation  for  diagnostic 
purposes.  The  white  rat  possesses  an  almost  com- 
plete immunity,  although  under  certain  circumstances 
it  can  also  be  succesfully  inoculated. 

The  dog  takes  the  disease  only  when  large  doses 
are  employed  or  when  the  virulent  substance  is  intro- 
duced into  the  vascular  system.  Fowls  are  refractory 
to  both  the  natural  and  experimental  disease  ;  but  this 
immunity  is  easily  overcome  :  cooling  a  fowl  to  38°, 
by  placing  it  in  a  current  of  cold  water,  is  sufiicient 
to  induce  the  development  of  the  disease  after  iuocu- 
lution.  These  fowls,  when  again  warmed,  recover. 
The  temperature  of  fowls  is,  therefore,  naturally  too 
high  to  admit  of  the  pullulation  of  the  charbon  bacil- 
lus. On  the  contrary,  that  oi frogs  is  too  low,  and  we 
only  succeed  in  infecting  these  animals  with  charbon 
when  they  are  heated  in  a  bath  to  35°. 

In  the  rabbit  and  the  gujnea  pig  the  inoculation  is  fol- 
lowed, at  the  end  of  ten  to  fifteen  hours,  by  a  marked 
local  oedema ;  the  temperature  is  elevated  from  one  to 


188  3Ianual  of  Veterinary  Microbiology. 

two  degrees.  Nevertheless,  the  appetite  only  fails  a 
few  hours  before  death.  The  latter  supervenes  in 
thirty-six  to  forty  hours  in  the  guinea  pig,  forty-eight 
to  sixty  in  the  rabbit;  the  animal  dies  in  coma  or 
after  slight  convulsions,  and  always  with  a  marked 
depression  of  temperature. 

The  autopsy  of  animals  which  have  succumbed  to 
the  inoculated  disease  is  interesting :  the  inoculated 
place  is  the  seat  of  a  jelly-like  cedematous  infiltration, 
of  a  faint  red  color.  This  oedema  is  found  in  natural 
cases  of  charbon  when  the  penetration  of  the  bacte- 
ridia  has  occurred  at  an  erosion  of  the  digestive  mu- 
cous membrane :  gloss-anthrax,  charbonous  angina. 
The  corresponding  lymphatic  glands  are  tumefied,  ec- 
chymosed,  and  surrounded  by  an  cedematous  zone. 
The  cedematous  fluid  and  the  blood  are  charged  with 
bacteridia.  The  spleen  is  much  enlarged,  difiluent, 
and  dark  in  color.* 

*  [We  have  little  reliable  information  as  to  the  extent  to  which 
anthrax  prevails  in  the  United  States  and  Canada.  Local  out- 
breaks have  been  reported  from  many  different  quarters,  but  the 
microscopical  and  laboratory  investigations  necessary  to  the  iden- 
tification of  the  disease  have  generally  been  lacking.  A  disease 
known  to  the  natives  as  "charbon  "  prevails  in  some  years  as  an 
epidemic  among  mules  in  certain  parts  of  Mississippi  (also  re- 
ported in  Louisiana  and  Arkansas).  This  disease  was  investigated 
and  described  as  charbon  by  Veterinarian  Creelman,  of  the  Mis- 
sissippi Agricultural  Experiment  Station,  and  the  diagnosis  con- 
firmed by  the  laboratory  investigations  of  Dr.  Connoway,  of  the 
Missouri  Experiment  Station.  {Miss.  Agric.  Exper.  Sta.  Bull. 
No.ll.) 

Material  from  the  same  source  (obtained  from  a  cow),  examined 
at  Washington,  was  found  to  contain  the  anthrax  bacillus.  {An. 
Rep.  Bureau  of  Animal  Industry,  1889-1890,  jj.  43.) 

An  extensive  outbreak  of  anthrax,  in  Illinois,  is  reported  by 


Microhic  Diseases  Individually  Considered.      189 

Etiology  and  j^afhogeny. — Diseased  animals  dissem- 
inate the  virus  in  their  fecal  dejections  and  urine, 
which  are  often  mixed  with  blood  and  therefore 
with  hacteridia;  frequently,  also,  the  blood  escapes  to 
the  exterior  directly  by  the  nasal  cavities.  Their  car- 
casses, all  parts  of  which  contain  the  virus,  are  more 
important  sources  of  contagion  ;  hence,  when  these 
carcasses  are  buried  without  any  precautions  being 
taken  to  destroy  the  charbonous  germs,  they  may 
become  the  starting  point  of  fresh  cases.  These 
bodies  become  more  directly  dangerous  when  the 
flesh  is  used  for  food. 

Contagion  by  direct  contact  is  comparatively  rare; 
it  occurs  when  a  person  inoculates  himself  with  char- 
bon  at  a  cut  or  any  other  recent  wound,  in  cutting  up 
a  charbonous  carcase ;  it  also  occurs  when  the  dis- 
ease follows  the  consumption  of  diseased  meat,  and 
finally,  by  transmission,  now  well  established,  from 
the  mother  to  the  foetus. 

Contagion  most  frequently  takes  place  by  indirect 
contact,  the  germs  having  been  previously  distributed 
in  the  surrounding  media.  The  floor  of  sheds,  the 
soil  and  vegetation  of  fields  occupied  by  diseased  ani- 
mals, become  soiled  by  their  dejections;  the  germs 
thus  deposited  may  contaminate  the  litter  and  fodder 
and  thus  gain  entrance  to  the  alimentary  canal  of 
herbivora.  It  is  not  necessary  in  this  case,  as  w^as  at 
first  believed,  that  the  animals  ingest  at  the  same  time 

Dr.  Trumbower.     {Rep.  Board  of  Live  Stock  Commissioners  of  Ilh., 
1893.) 

A  few  cases  in  cattle,  in  which  the  diagnosis  was  confirmed  by 
competent  bacteriologists  are  reported  from  Delaware.  (Fifth  An, 
Rep.  of  the  Del.  College  Agric.  Experiment  Sta.,  1892,  p.  45.) — D.] 


190  Manual  of  Veterinary  Microbiology. 

substances  capable  of  wounding  the  mucosa,  thus 
opening  the  way  for  the  bacteridia.  It  has  been 
shown  that  the  spores  of  charbon  can  be  absorbed  in 
the  absence  of  all  intestinal  wounds.  However,  the 
non-sporulated  bacilli'  are  killed  by  the  gastric  juice 
so  that  their  action  can  only  take  efiect  in  the  passages 
anterior  to  the  stomach,  and  hy  a  solution  of  contin- 
uity. Experiment  has  shown  that  the  addition  to 
contaminated  fodder  of  substances  capable  of  ex- 
coriating the  mucosa  (thistles,  husks  of  barley)  in- 
creases the  mortality  from  charbon.  At  the  wounds 
thus  produced  there  is  first  developed  a  tumor,  from 
which  invasion  proceeds  by  way  of  the  lymphatics. 

We  bave  seen  that,  if  the  charbon  bacilli  have  them- 
selves great  resistance,  this  faculty  is  possessed  to  a 
still  greater  degree  by  their  spores.  It  is,  morever, 
under  this  last  form  that  the  contagion  of  charbon 
persists  on  certain  farms  in  such  a  way  as  to  give  the 
disease  an  endemic  character.  The  contagion  having 
once  been  deposited  on  a  field,  even  on  a  limited  part 
of  the  same,  it  remains  there  for  years,  contaminating 
the  vegetation  which  grows  upon  it.  The  spores  have 
been  found  on  the  surface  of  the  ground  above  a  grave 
closed  for  twelve  years.  The  disease  occurs  during 
the  pasturing  season  or  in  winter,  according  as  the 
herbage  is  consumed  while  growing  or  after  harvest- 
ing, in  the  form  of  hay.  The  most  frequent  cause  of 
these  endemic  foci  resides  in  the  manner  of  burial  of 
charbonous  carcases  :  in  spite  of  the  layer,  of  greater 
or  less  thickness,  by  which  they  are  covered,  the  spores 
produced  in  these  bodies  *  find  their  way  to  the  sur- 

*  [It  seems  to  be  well  established  that  spores  are  not  formed  in 


Microhlc  Diseases  Individually  Considered.      191 

face.  It  is  asserted  that  tliis  migration  is  chiefly  due 
to  the  agency  of  earth-worms.  We  know  that  these 
worms,  in  excavating  the  passages  through  which  they 
wander,  swallow  a  certain  quantity  of  earth  which 
they  then  expel  in  the  form  of  tortuous  rolls ;  we  also 
know  that  they  make  regular  nocturnal  peregrina- 
tions to  the  surface  of  the  soil  in  order  to  feed  on  the 
herhage.  Now,  M.  Pasteur  has  found,  in  these  little 
rolls  of  earth  deposited  above  a  grave  containing  a 
charbonous  carcase,  the  spores  or  germ  corpuscles 
of  the  disease.  These  spores  do  not  necessarily  always 
remain  limited  to  the  part  of  the  field  on  which  they 
have  been  deposited ;  they  may  be  more  or  less  widely 
disseminated  by  winds,  and  more  especially  by  water. 
If  we  admit  as  established  the  possibility  of  the 
multipUcation  of  the  bacilli  of  charbon  in  swampy 
soil  we  can  readily  account  for  the  persistence  of  the 
disease  in  certain  localities. 

The  charbon  bacilli  may  penetrate  into  the  blood 
directly  or  indirectly;  in  this  last  case  they  first  make 
their  way  into  the  tissues,  multiply  there,  and  excite 
an  inflammatory  engorgement,  then  gain  the  lym- 
phatic glands  and,  finally,  the  blood.  They  then  act 
by  a  complex  mechanism.  By  reason  of  their  aerobic 
character  they  rob  the  blood  of  part  of  its  oxygen  and 
thus  give  rise  to  asphyxia.  This  asphyxiating  action, 
however,  is  contradicted  by  the  investigations  of 
M.  Chauveauwho  has  demonstrated  the  presence  of  a 
normal  proportion  of  oxygen  in  the  blood  of  a  sheep 

the  blood  or  organs  of  buried  cadavers  [Feser,  Kitasato,  Kitt) ;  they 
are  found,  however,  on  the  surface  of  these  bodies  where  they  are 
soiled  with  blood,  excretions,  etc.,  and  also  in  the  digestive  canal 
both  before  and  after  death. — D.] 


192  Manual  of  Veterinary  31k-rohiolo(jy. 

ill  the  last  stage  of  charbon.  It  is  especially  by  its 
secretions  that  the  bacteridium  acts  upon  the  organ- 
ism. The  nature  of  these  substances  is  as  yet  im- 
perfectly understood,  but  their  action  is  demonstrated 
by  the  following  experiment:  M.Chauveau transfused 
to  a  healthy  sheep  a  large  quantity  of  blood  coming 
from  a  sheep  affected  with  charbon,  and,  as  a  conse- 
quence, noticed  the  development  of  the  general  symp- 
toms of  the  disease.  This  immediate  result  can  only 
be  explained  as  a  chemical  poisoning,  an  opinion 
which  was,  moreover,  confirmed  by  the  microscopic 
examination,  which  showed  the  disappearance  of  the 
bacilli  from  the  transfused  sheep.  It  is  to  this  in- 
toxication that  we  must  ascribe  the  phenomena  of 
nervous  depression  or  temporary  excitement,  which 
are  so  marked  in  charbonous  subjects. 

Charbonous  blood  filtered  through  porcelain  acts  on 
the  red  corpuscles  of  normal  blood,  rendering  them 
■viscid  and  glutinous.  This  property  is  communicated 
to  it  by  the  substances  secreted  by  the  charbon  bacilli 
and  it  explains  the  peculiar  alteration  of  the  blood 
in  this  disease. 

Finally,  the  bacilli  act  mechanically  ;  on  account  of 
their  number  and  the  abnormal  viscidity  of  the  blood, 
they  form  plugs  in  the  interior  of  the  capillary  ves- 
sels, thus  occasioning  blood  stases  and  superficial  and 
deep  hemorrhages.  This  is  undoubtedly  the  cause  of 
the  final  passage  of  the  bacteridia  into  the  milk, 
urine,  and  through  the  placenta ;  it  is  also  the  cause 
of  the  large  and  characteristic  sw^elling  of  the  spleen, 
as  well  as  of  the  hemorrhages  and  general  circulatory 
disturbance. 

Attenuation.     Vaccinations. — The  virulence  of  char- 


Microhic  Diseases  Individually  Considered.       193 

bon  cultures  is  very  stable  ;  this  is  due  to  the  pres- 
ence of  the  spores  which  are  little  subject  to  change. 
When  it  is  desired  to  attenuate  these  cultures  it  is 
necessary  to  begin  by  preventing  the  formation  of 
spores.  Pasteur  succeeded  in  this  by  cultivating  the 
charbon  bacilli  at  the  temperature  of  42°  to  43°. 
Multiplication  of  the  bacilli  still  continues,  but  spores 
are  no  longer  formed.  Now,  if  such  cultures  are 
kept  in  contact  with  the  air  their  virulence  rap- 
idly diminishes  ;  after  twelve  days  they  no  more  kill 
adult  guinea  pigs,  and  vaccinate  the  rabbit  and  the 
sheep  ;  the  power  of  vegetation,  however,  still  per- 
sists, and  is  absolutely  extinguished  only  at  the  end  of 
one  and  a  half  months,  on  an  average.  The  bac- 
teridium  which  has  become  asporogenous  at  the  tem- 
perature of  42°  to  43°  then  loses  its  virulent  properties, 
retaining  only  those  of  an  ordinary  saprogenic  mi- 
crobe, and,  finally,  it  loses  all  vitality. 

The  culture  loses  its  pathogenic  power  little  by  lit- 
tle ;  it  ceases  to  be  fatal  first  for  the  large  animals, 
then  for  small  adults,  and  finally  for  small  animals 
only  a  few  days  old.  ISTow,  each  degree  of  virulence 
can  be  perpetuated  separately  by  cultivating  at  42° 
to  43°  the  different  varieties  obtained,  each  of  these 
varieties  transmitting  its  special  virulence  to  its  de- 
scendants. The  degree  of  attenuation  of  each  of 
these  varieties  can  be  preserved  if  the  precaution  be 
taken  to  frequently  transfer  to  fresh  culture  media ; 
but  it  is  not  possible  to  entirely  avoid  the  attenuation 
which  finally  takes  place.  In  order  to  definitely  fix 
these  varieties  it  suffices  to  return  them  to  37°  ;  they 
then  form  spores  possessing,  in  embryo,  the  special 
17 


194  Manual  of  Veterinary  Microbiology. 

virulence  of  the  bacilli  from  which  they  came  and 
capable  of  transmitting  this  virulence  to  new  gen- 
erations of  bacilli  cultivated  at  37°. 

The  least  virulent  varieties  obtained  produce  a  be- 
nignant disease  which  leaves  behind  it  immunity  for 
the  varieties  less  attenuated,  and  thus  are  obtained 
vaccines  of  different  degrees  of  intensity,  which  may 
be  employed  in  succession.  In  practice  two  vaccines 
only  are  used,  of  which  one  or  two  drops  are  in- 
jected at  an  interval  of  ten  days. 

In  the  general  part  we  have  described  the  other 
methods  of  attenuation  of  the  charbon  bacillus — by 
compressed  oxygen,  by  heat  and  by  antiseptics — and 
the  vaccination  processes  which  have  been  derived 
from  them. 

Symptomatic  charbon* 

This  disease,  formerly  confounded  with  charbon 
properly  so  called,  has  been  separated  from  the  latter 
as  a  result  of  the  investigations  of  MM.  Arloing, 
Cornevin,  and  Thomas.  It  is  characterized,  first,  by 
the  symptoms  of  a  more  or  less  intense  fever  and  by 
the  appearance  of  a  specific  tumor  upon  the  body, 
neck,  or  upper  part  of  the  limbs.  This  tumor  is  al- 
most constantly  found  in  the  muscular  masses  ;  it  con- 
sists, at  first,  of  a  painful  and  progressive  inflamma- 
tory engorgement,  of  firm  and  uniform  consistence ; 
it  rapidly  extends  in  area  and  in  depth  and,  later,  be- 
comes insensible,  crepitant,  and  resonant  at  its  center 
(emphysemato-gangrenous  tumor).   The  general  symp- 

*  [Also  occasionally  referred  to  in  this  work  as  "  bacterial  char- 
bon." Synonyms  :  Symptomatic  anthrax,  black-quarter,  infectious 
emphysema;  iai.  Sarcophysemahsemostaticumbovis;  (?€/-.  Rausch- 
brand.— D.] 


Microhic  Diseases  Individually  Considered.       195 

toms  become  aggravated  with  the  progressive  evolu- 
tion of  the  local  lesion  and  the  subject  succumbs  in 
thirty-six  to  forty-eight  hours.  When  the  disease  has 
been  somewhat  prolonged,  other  tumors  with  the 
same  characters  not  infrequently  supervene.  The  dis- 
tribution of  these  secondary  tumors  is  not  in  relation 
with  that  of  the  lymphatics ;  their  development  ap- 
pears to  take  place  through  the  intermediation  of  the 
blood. 

At  the  autopsy  the  local  lesion  is  the  predominant 
feature,  the  invaded  muscles  are  friable  and  more  or 
less  darkened  in  color  (charbou);  their  fibrous  bundles 
are  readily  dissociated ;  the  fibers  retain  their  striation 
but  their  contents  is  broken  up  into  hyaline,  vitreous 
blocks  (hyaline  degeneration).  The  intra-muscular 
connective  tissue,  as  well  as  that  which  surrounds  the 
muscular  masses,  is  thickened  and  infiltrated  with  a 
yellowish  serosity ;  this  cedema  sometimes  assumes  con- 
siderable proportions.  The  formation  of  gas,  inherent 
to  the  life  of  the  germ,  causes  the  detachment  of  the 
tissues,  a  true  localized  emphysema  in  the  central  part 
of  the  tumor.  The  gases  produced  are,  chiefly,  car- 
bonic acid  and  marsh  gas. 

The  lymphatic  glands  in  relation  to  the  tumor  are 
reddened,  ecchymosed  and  infiltrated. 

After  death  the  bodies  very  rapidly  putrefy. 

The  animals  which  spontaneously  contract  the  dis- 
ease are  cattle,  sheep  and  goats.  The  receptivity  of 
the  first  is  not  the  same  at  all  ages ;  calves  of  less  than 
six  months  do  not  contract  the  natural  disease,  and 
cattle  of  over  four  or  five  years  also  seem  to  escape. 

Microbe. — The  pathogenic  agents  in  this  disease  are 
straight  rods,  isolated  or  occasionally  associated  in  pairs, 


196  Manual  of  Veterinary  3licrobiotogy. 

measuring  in  the  adult,  non-sporulated  condition  5/i 
to  8//  by  1// ;  after  fruiting  they  may  attain  larger  di- 
mensions— 10//  by  I'Sju;  as  long  as  their  contents  are 
homogeneous  they  are  cylindrical,  but  their  form 
changes  with  the  appearance  of  the  spores;  generally 
the  spore  is  terminal  and  gives  the  bacillus  a  bell- 
clapper  or  club-shaped  appearance;  sometimes  it  is 
central,  the  bacillus  then  becoming  spindle-shaped. 
The  spore  is  solitary,  ovoid,  and  very  distinct;  it  oc- 
cupies one-third  of  the  length  of  the  element. 

The  bacillus  Chauvoei  is  endowed  with  oscillatory 
motion.  It  is  strictly  anaerobic;  hence  we  should 
not  expect  to  find  it  in  the  blood,  at  least  during  life ; 
after  death,  when  the  oxygen  is  no  more  renewed  by 
the  pulmonary  exchanges,  it  penetrates  into  this  fluid. 

Action  of  2}hysical  and  chemical  agents. 

^'    '  The  virus  withstands  extreme  cold  and 

^*^^  •        after  being  dried  also  resists  for  a  con- 

^^  0  siderable  time  the  action  of  high  tem- 

Bacilliofsvmp-P^^^^^''^^'  i*  ^^  ^^'^  destroyed  by  ex- 
tomatic  charbon,  posure  for  two  hours  to  80°,  or  for 
nou-sporulated  twenty  minutes  to  100°;  on  the  other 
and  sporulated.  }^rjj-,(]  j^^  perishes  in  two  minutes  in 
(M.  and  L.)  ,     .,. 

boiling  water. 

The  serosity  dried  at  about  35°  retains  its  virulence 
for  more  than  two  years. 

Putrefaction  has  no  effect  on  the  bacillus  of  symp- 
tomatic charbon. 

The  bacllh,  when  they  have  escaped  from  the  ca- 
davers and  been  deposited  upon  the  soil,  preserve 
their  virulence  for  a  long  time  if  the  external  condi- 
tions permit  of  their  rapid  desiccation  ;  under  other 
conditions  they  are  more  or  less  quickly  attenuated  and 


Microbic  Diseases  Individually  Considered.      197 

finally  destroyed  by  the  oxygen  of  the  air.  The  same 
thing  occurs  when  they  have  penetrated  to  a  slight 
depth  in  permeable  soil.  But  when  they  are  buried 
at  a  sufficient  depth,  especially  in  a  compact  clayey 
soil,  they  are  preserved  for  a  considerable  time  on  ac- 
count of  the  absence  of  oxygen  and  light,  and  they 
may  even,  by  virtue  of  their  anaerobic  faculty,  propa- 
gate themselves  there. 

Strong  antiseptics  are  fatal  to  the  bacillus  Chauvcei ; 
Arloing,  Cornevin,  and  Thomas  have  observed  this 
toxic  action  after  twenty-four  hours'  contact  with  sub- 
limate, at  1  to  5,000,  chlorine  gas,  and  two  per  cent 
solution  of  carbolic  acid  ;  on  the  other  hand,  sulfurous 
acid,  quick  lime,  and  90  per  cent  alcohol  do  not  de- 
stroy its  virulence. 

Cultures. — Cultures  of  this  microbe  are  very  difficult 
to  obtain ;  they  are  only  possible  when  excluded  from 
oxygen,  in  a  vacuum,  or  in  presence  of  an  inert  gas, 
such  as  carbonic  acid.*  Bouillons  to  which  have 
been  added  glycerin  and  ferrous  sulfiite,  or  gelatin 
and  sugar,  are  the  media  to  be  preferred.  The  fluid 
rapidly  becomes  turbid  and  the  seat  of  an  intense  dis- 
engagement of  gas  ;  it  exhales  a  pronounced  odor  of 
rancid  butter. 

Attempts  at  cultivation  on  solid  media  have  also 
been  successful.  Upon  gelatin  there  are  produced 
spherical  verrucose  colonies,  which  fluidify  the  me- 
dium and  give  rise  to  a  lively  production  of  gas  ;  cult- 
ures upon  agar  have  a  penetrating  acid  odor.  Viru- 
lence does  not  long  persist  in  generations  obtained  by 

*  ["  Grows  in  an  atmosphere  of  hydrogen  but  not  in  carbon  di- 
oxide."    Sternberg:  Manual  of  Bacteriology,  p.  i94. — D.] 


198  Manual  of  Veterinary  Microbiology. 

artificial  culture  ;  it  becomes  obliterated  in  four  or  five 
transfers. 

The  material  for  inoculation  of  culture  media  maybe 
taken  from  the  juice  obtained  by  scraping  the  center 
of  a  tumor,  from  the  peritoneal  serosity,  and  from  the 
blood ;  but  they  only  appear  in  this  last  fluid  after 
death ;  as  they  are  present  in  small  numbers  it  is  well 
to  allow  them  to  multiply  by  keeping  a  quantity  of 
this  blood  in  the  incubator  for  twenty-four  hours. 

Research  and  coloration. — The  bacillus  Chauvoei  ex- 
ists in  great  abundance  in  the  muscular  tumor,  sus- 
pended in  the  fluid  with  which  it  is  infiltrated  and 
which  is  interposed  between  the  contractile  elements. 
In  the  last  moments  of  life  and  after  death  it  is  also  met 
with  in  small  numbers  in  the  blood ;  finally,  it  exists  in 
abundance  in  the  bile  and  in  the  peritoneal  serosity. 

Simple  methods  of  staining  are  alone  successful; 
the  various  hydro-alcoholic  solutions  are  available  for 
this  purpose,  but  Loffler's  method  should  be  preferred 
for  sections. 

Experimental  inoculations. — The  species  to  which  it 
is  possible  to  communicate  the  experimental  disease 
are  the  ox,  sheep,  goat,  and  guinea  pig.  The  rabbit  is 
refractory.  The  ass  and  the  horse  only  contract  a  local 
engorgement. 

The  receptivity  of  the  various  species  for  this  bacillus 
sufiiciently  difierentiates  it  from  that  of  Pasteur's  sep- 
ticsemia  which  it  much  resembles  in  its  physical  char- 
acters, staining  proclivities,  and  its  anaerobic  faculty, 
and  in  the  emphysemato-gangrenous  lesions  which  it 
occasions.  The  septic  bacillus  is  pathogenic  for  all 
species  except  the  ox ;  the  bacillus  of  symptomatic 


3Iicrohic  Diseases  Indiindually  Considered.       199 

cliarbon  is  pathogenic  only  for  ruminants  and  the 
guinea  pig. 

Dermic  inoculation  with  the  lancet  or  by  superficial 
scarifications  is  nearly  always  unsuccessful,  whilst  the 
introduction  of  the  virus  into  the  subcutaneous  cellu- 
lar tissue  or  into  the  muscular  tissue  gives  positive  re- 
sults. However,  it  is  necessary  to  take  into  account 
the  dose  injected  and  the  place  in  which  the  injection 
is  made.  Very  small  doses  do  not  produce  the  dis- 
ease but  confer  immunity;  similarly,  a  dose  which 
would  be  fatal  if  injected  in  a  favorable  place  is  inof- 
fensive when  inoculated  in  the  cellular  tissue  of  the 
tail  and  of  the  extremity  of  the  limbs.  The  experi- 
ments of  M.  Arloing  have  shown  that  this  local  im- 
munity, w^hich  had  been  established  by  clinical  obser- 
vation, depends  upon  the  greater  density  of  the  con- 
nective tissue  and  on  the  lower  temperature  of  these 
regions.  He  succeeded  in  overcoming  this  immunity 
by  heating  the  region  or  by  lacerating  its  cellular 
tissue. 

After  the  insertion  of  the  virus  in  the  subdermic  tis- 
sue there  results  a  painful  and  progressive  inflamma- 
tory engorgement  wiiich  extends  to  neighboring  re- 
gions and  in  the  guinea  pig  leads  to  death  in  twenty- 
four  to  forty-eight  hours. 

The  intra-venous  inoculation  of  small  doses,  but 
doses  which  would  be  fatal  by  the  subcutaneous 
method  (three  to  five  drops  of  juice  in  young  bovines, 
three-tenths  of  a  drop  in  sheep),  excites  a  rather  in- 
tense febrile  reaction ;  tumors  are  not  produced  unless 
some  of  the  virus  has  been  deposited  in  the  cellular 
tissue  surrounding  the  bloodvessel.  The  subject  thus 
inoculated  is  vaccinated  against  the  temporary  reac- 


200  Manual  of  Veterinary  Microbiology. 

tion  of  a  second  intra- venous  injection,  and  also  against 
the  subcutaneous  inoculation  of  an  otherwise  mortal 
virus;  the  reaction  of  the  latter  then  consists  only  in 
the  formation  of  a  curable  abscess,  the  pus  of  which 
contains  the  virulent  germs. 

If  the  dose  w^aich  can  be  tolerated  in  the  vessels  is 
exceeded,  the  typical  disease  ensues  with  the  develop- 
ment of  tumors.  Similarly,  if,  after  the  intra- vascular 
injection  of  a  vaccinating  dose,  a  hemorrhage  is  pro- 
duced in  the  connective  tissue,  a  specific,  fatal  tumor 
appears  in  the  place  of  the  solution  of  vascular  con- 
tinuity, the  bacilli  having  penetrated  into  their  media 
of  predilection. 

The  disease  is  transmissible  by  way  of  the  respira- 
tory passages,  the  result  being  the  same  as  by  the  blood- 
vessels. Finally,  the  disease  can  be  transmitted  by 
way  of  the  intact  digestive  canal  if  the  virus  is  very 
active  ;  the  tumors  then  appear  in  places  remote  from 
the  point  of  entry. 

Etiology  and  j^c^thogeny. — Symptomatic  charbon  is 
endemic  in  certain  countries;  it  prevails  especially 
during  summer,  its  ravages  being  however  less  im- 
portant than  those  of  bacteridian  charbon.  Animals 
inoculate  themselves  accidentally,  and  as  small  doses 
confer  immunity  and  this  is  transmitted  from  the 
mother  to  the  foetus,  it  results  that  part  of  the  animals 
exposed  to  the  contagion  escape  its  fatal  efiects.  But 
those  which  at  first  receive  a  suflacient  dose  quickly 
succumb. 

The  virus  seems  to  be  capable  of  entering  by  diflfer- 
ent  ways.  Wounds  of  the  external  integument  in 
favorable  regions  are  more  especially  suited  to  its  evo- 
lution ;  but  the  inhalation  of  dust  charged  with  dried 


Microbic  Diseases  Individually  Considered.      201 

virus,  as  well  as  the  ingestion  of  forage  soiled  by  very 
active  virulent  matters,  can  also  occasion  the  disease. 
In  the  case  of  cutaneous  wounds,  the  characteristic 
tumor  develops  at  the  place  of  inoculation  itself;  in 
the  two  latter  contingencies  the  bacilli  multiply  in  the 
blood  and  determine  tumors  in  places  where  they  meet 
with  an  opening  by  which  they  may  penetrate  into 
the  connective  or  muscular  tissue.  Rupture  of  some 
of  the  fibers  of  the  muscles,  alteration  of  the  vascular 
endothelium  (perhaps  by  the  products  of  the  bacilli), 
the  production  of  even  a  slight  wound  which  may  be 
overlooked,  are  all  so  many  factors  on  which  depend 
the  seat  of  the  primary  and  secondary  tumors. 

Attenuations.  Preventive  inoculations. — The  virus  be- 
comes spontaneously  attenuated  when  it  is  left  in  con- 
tact with  the  air;  diminution  of  its  virulence  can  be 
obtained  artificially  by  means  of  antiseptics  and  heat. 
The  latter  agent  supplied  to  MM.  Arloing,  Cornevin, 
and  Thomas,  the  means  of  preparing  virus  of  various 
degrees  of  intensity.  The  natural  serosity  of  the 
specific  lesions  can  be  attenuated  to  difi'erent  degrees 
by  a  temperature  of  from  65°  to  70°,  maintained  for  a 
greater  or  less  length  of  time.  These  authors,  how- 
ever, operated  by  preference  with  serosity  dried  at  the 
temperature  of  30°  to  35°;  the  dried  virus  is,  in  reality, 
more  fixed  than  the  fluid  serosity,  because  the  spores 
are  much  more  resistant  when  dry  than  when  in  a 
moist  condition.  This  dried  virulent  substance  with- 
stands temperatures  of  80°  to  90°  without  losing  any 
of  its  activity;  reduced  to  powder  and  moistened, 
then  brought  to  temperatures  varying  between  60°  and 
110°,  it  becomes  progressively  attenuated.  The  virus, 
attenuated  to  such  an  extent  that  it  is  no  more  fatal, 


202  Manual  of  Veterinary  Microbiology. 

vaccinates  the  organism  against  more  active  virus. 
The  French  authors  recommend  the  successive  em- 
ployment of  two  vaccines,  one  exposed  to  100° 
the  other  to  90°,  during  seven  hours.  These  two 
vaccines  are  dry  when  taken  from  the  oven  in 
which  they  have  been  prepared ;  the  dose  employed 
is  one  centigram  of  the  powder  diluted  in  a  gram  of 
water  for  each  animal.  The  vaccine  prepared  at  100° 
is  first  used,  and  then,  after  eight  days,  the  other. 
The  inoculations  are  made  in  the  cellular  tissue  of  the 
ear,  or  in  the  internal  face  of  the  end  of  the  tail.  The 
autumn  or  the  end  of  winter  are  the  seasons  selected 
for  the  operation.  It  is  necessary  to  guard  against  in- 
oculation during  very  hot  weather  as  an  elevated 
temperature  increases  the  activity  of  the  virus. 

The  consequences  of  the  vaccinal  inoculation  are 
local  and  general.  At  the  inoculated  point  an  en- 
gorgement develops,  generally  of  small  extent  and 
healing  spontaneously.  At  the  same  time  there  is 
observed  a  febrile  reaction,  which  indicates  the  exist- 
ence of  the  disease  in  a  mild  form. 

Kitt  recommends  a  single  vaccine  prepared  at  90°. 

When  the  virus  has  been  thus  artificially  attenuated 
it  can  regain  its  original  activity  by  successive  pas- 
sages through  the  bodies  of  young  guinea  pigs,  and 
also  under  the  influence  of  lactic  acid,  etc.,  as  already 
described. 

Animals  can  also  be  vaccinated  by  injection  of  the 
natural  virus  either  in  the  cellular  tissue  or  into  the 
blood.  We  have  seen  above,  that  inoculation  of  small 
doses  in  the  connective  tissue  confers  immunity  in 
place  of  the  disease,  and  that  the  blood  tolerates  com- 
paratively large  doses  of  the  virus.     Injection  into 


Microhic  Diseases  Individually  Considered.      203 

the  veins,  however,  must  be  made  with  the  greatest 
care  in  order  to  avoid  the  accidental  deposition  of  any 
of  the  virus  in  the  surrounding  tissue,  hence,  in  prac- 
tice, the  attenuated  viruses  are  generally  preferred  to 
the  natural  viruses,  for  the  production  of  immunity. 

Bouget  of  the  pig.* 

This  disease,  peculiar  to  the  pig,  is  infectious  and 
contagious ;  it  chiefly  attacks  adult  animals  and  those 
of  the  improved  breeds.  It  manifests  itself  by  a  very 
intense  febrile  reaction,  by  red  or  purple  patches,  at 
first  discreet  and  afterward  confluent,  upon  the  integu- 
ment, by  a  diarrhoea  more  or  less  intense,  succeeding 
to  constipation,  and  often  by  cough.  The  redness  of 
the  skin  may  be  absent  in  very  acute  cases. 

The  duration  of  the  disease  is  always  short,  on  an 
average,  two  days ;  it  may,  however,  last  four  or  five 
days,  and,  on  the  other  hand,  may  occasionally  be  al- 
most fulminating  in  character. 

Death  is  the  usual  termination,  but  a  considerable 
proportion  of  pigs  may  recover.  Moreover,  all  the 
the  pigs  which  have  been  in  contact  with  diseased 
animals  do  not  necessarily  contract  the  disease. 

The  autopsy  discloses  a  general  congested  condition 
of  the  capillaries.  There  is  injection  and  serous  infil- 
tration of  the  skin  and  subcutaneous  cellular  tissue, 
injection  with  petechise  and  sero-fibrinous  exudation 
of  the  peritoneum,  pleura  and  pericardium,  changes 
of  the  same  kind  in  the  gastro-intestinal  canal  in 
which  the  mucosa  is  reddened,  thickened  and  infil- 

*  [Eng.  Swine  erysipelas:  Ger.  Rothlanf.     The  disease  has  not 
been  recorded  in  the  United  States  or  Canada. — D.] 


204  Manual  of  Veterinary  Microbiology. 

trated;  in  many  places  the  epithelium  is  desquamated, 
and  occasionally  there  are  ulcerations  in  way  of  forma- 
tion. 

The  blood  vascular  glands  (spleen,  lymph  nodes, 
Peyer's  patches)  are  tumefied  by  congestion,  exuda- 
tion and  extravasation ;  the  kidneys,  lungs  and  heart 
always  show  injection  and  even  extravasations.  In 
rare  cases  there  are  multiple  lesions  of  broncho-pneu- 
monia. 

The  germ  of  rouget  is  a  very  fine,  cylindrical  bacil- 
lus recalling  that  of  mouse  septicaemia ;  (1)  it  measures 
Ifi  to  2//  in  length  by  0-1//  to  0-1 5//  in  thickness.  It  is 
found  in  the  blood,  especially  in  the  fine  capillaries,  in 
contact  with  their  internal  wall ;  it  also  exists  in  the 
exudates  and  in  all  the  diseased  organs  :  liver,  spleen, 
kidneys,  lymphatic  glands,  marrow  of  bones,  etc.;  in 
the  fsecal  matters,  and  in  the  urine.  This  agent  should 
not  be  confounded  with  a  large  rod  which  is  found  in 
the  blood  in  most  diseased  pigs  and  which  does  not 

(1)  Mouse  septicaemia  was  obtained  experimentally  by  Koch,  by 
inoculating  putrefied  blood  under  the  skin  of  those  animals.  The 
disease  is  easily  transmitted  to  house  mic^T\hilst  field  mice  are 
refractory.  The  microbes  show  much  resemblance  with  those  of 
rouget;  they  have  the  same  form,  the  same  dimensions,  are  rather 
anaerobic  than  aerobic,  and  both  take  the  Gram  and  Weigert 
stains.  In  gelatin,  stab  cultures  of  mouse  septicaemia  give  colo- 
nies with  radiating  branches  like  those  of  rouget,  but  the  rays  are 
confounded  with  each  other,  whilst  those  of  rouget  are  distinct ; 
gelatin  is  not  fluidified  by  either.  Potato  is  poorly  or  not  at  all 
adapted  to  their  vegetation.  Both  become  much  elongated  in 
cultures.  The  pigeon  succumbs  with  equal  rapidity  to  rouget  and 
mouse  septicaemia.  The  rabbit,  on  the  other  hand,  is  much  more 
sensitive  to  the  former  of  these  diseases.  Both  produce,  in  the 
pigeon  and  the  mouse,  enlargement  of  the  spleen  and  congestive 
lesions  of  the  different  organs. 


Microhic  Diseases  Individually  Considered.      205 

show  any  specific  pathogenic  property.  This  last 
germ  is  never  seen  in  the  experimental  disease  and 
probably  comes  from  a  secondary  invasion  occurring 
in  the  diseased  animal.  The  point  of  departure  of 
this  collateral  infection  appears  to  be  the  intestine,  in 
which  the  bacillus  just  mentioned  is  found  in  abun- 
dance; it  is  present  in  the  blood  in  smaller  numbers 
the  further  removed  the  latter  is  from  the  abdominal 
cavity. 

Pasteur  and  Tliuillier,  who  first  described  the  bacil- 
lus of  rouget,  describe  it  as  of  a  figure  8  form,  but 
this  was  an  error  of  observation  which  our  staining 
methods  and  improved  instruments  have  corrected. 

The  bacillus  of  rouget  is  non-motile. 

Cultures. — The  bacillus  of  rouget  is  especially  ana- 
erobic but  it  also  grows  in  contact  with  the  air ;  it 
multiplies  at  a  temperature  as  low  as  20°,  but  grows 
especially  well  in  the  incubator. 

The  blood  and  the  pulp  of  the  various  diseased  or- 
gans may  be  used  for  the  inoculation  of  culture  media. 
This  material  will  more  likely  be  pure  when  taken 
from  a  part  at  some  distance  from  the  abdominal  cav- 

The  germ  grows  well  on  the  various  culture  media : 
on  potato,  especially  in  presence  of  oxygen,  the  growth 
is  feeble. 

In  bouillon  it  produces,  after  forty-eight  hours,  a 
slight  uniform  turbidity,  which  afterward  becomes  de- 
posited as  a  whitish  gray  sediment. 

Stab  cultures  in  gelatin  are  characteristic.  The 
germ  multiplies  especially  in  the  deeper  parts  and 
forms  along  the  course  of  the  puncture  a  track  from 
which  radiate  silky  tufts,  giving  to  the  whole  the  as- 


206  31anual  of  Veterinary  3Iicrobiology . 

pect  of  a  bottle  brush.  This  characteristic  form  is 
only  obtained  with  gelatin  of  firm  consistence.  The 
bacillus  of  rouget  appreciably  lengthens  in  its  cul- 
tures. 

Research    and   coloration. — The  specific  germ   can 
Fig.  8.  ^^  demonstrated  in  the  blood,  in  the 

,      .  fluid  exudates,  and  in  sections  of  the 

^  T-  various  tissues  afl:ected;  on  account 

**    ^^  of  its  small  size  it  is  advisable  to  ex- 

Bacilli:  1,  of  amine  only  stained  preparations  and 
pneumo-enter  i  t  i  s  to  employ  a  magnification  of  800  di- 
""It-rM'fndM"'  ^"^^^^^'«' ^*  ^east.  The  bacillus  of  rou- 
^^  ■        ■  ^"  get  is  stained  by  the  hydro-alcoholic 

solutions  of  all  the  aniline  colors  ;  the  color  is  not  re- 
moved by  the  reactions  of  Gram  and  Weigert. 

ExiJerimental  inoculations. — The  bacilli  of  rouget  are 
fatal  for  the  pig,  rabbit,  mouse  and  pigeon.  The  three 
last  species  are  especially  sensitive  and  succumb  to 
subcutaneous,  intra-peritoneal,  or  intra-venous  inocu- 
lations of  a  virulent  product,  whether  natural  or  de- 
.  rived  from  culture. 

Subcutaneous  inoculation  may  fail  in  the  pig ;  in- 
gestion, although  generally  communicating  the  disease, 
is  also  uncertain  in  its  results.  The  mouse  and  the 
pigeon  succumb  in  two  to  four  days;  the  pigeon  takes 
the  form  of  a  ball  of  feathers,  as  in  cholera;  the  rab- 
bit dies  in  three  to  six  days.  The  lesions  noticed  at 
the  autopsy  consist  of  a  hypertrophy  of  the  spleen 
with  congestion  of  the  liver  and  lymphatic  glands. 

The  guinea  pig,  rat,  dog,  and  chicken  are  refractory 
to  experimental  inoculation. 

Etiology  and  pathogeny. — Although  some  tests  of  in- 
fection by  the  digestive  passage  performed  in  Germany 


Microbic  Diseases  Individually  Considered.      207 

by  Lydtin  were  unsuccessful,  there  is  reason  to  believe 
that,  under  natural  conditions,  the  virus  gains  entrance 
by  the  digestive  canal. 

The  virulent  matter  ingested  by  healthy  pigs  will 
consist  especially  of  the  intestinal  dejections  of  the 
diseased.  Lack  of  proper  attention  to  the  feeding 
troughs,  and  defective  conditions  of  the  pens  (ventila- 
tion, lighting,  cleanliness)  are  of  a  nature  to  favor  the 
propagation  of  rouget,  as  well  as  of  other  diseases  of 
the  pig. 

Adult  hogs,  especially  those  of  the  improved  breeds 
(English),  are  most  liable  to  contract  the  disease ; 
young  pigs  and  those  of  native  breed  are  more  resist- 
ant. 

Attenuation.  Vaccination. — Rouget  of  the  pig  be- 
comes well  acclimated  in  the  pigeon  and  the  rabbit, 
and  in  these  two  species  acquires  great  virulence ;  but 
whilst  its  repeated  passage  through  the  organism  of 
the  pigeon  renders  it  more  active  for  the  pig,  passage 
through  the  rabbit,  on  the  contrary,  diminishes  its 
virulence  for  the  pig.  This  attenuation,  after  a  certain 
time,  is  such  that  the  virus  coming  from  the  rabbit 
no  more  kills  the  pig;  it,  however,  makes  it  sick  and 
confers  immunity  on  it  against  strong  virus.  The  at- 
tenuation thus  obtained  persists  in  cultures  afterward 
made  in  ordinarv  bouillon  and  these  cultures  can  be 
used  to  vaccinate  the  pig. 

In  practice  two  vaccines  only  are  employed,  and 
these  in  succession  at  ten  days  interval ;  a  feeble  vac- 
cine is  used  first  and  then  a  second,  the  virulence  of 
which  is  much  stronger. 

Young  pigs  being  much  less  susceptible  to  the  dis- 
ease and  therefore  to  the  virus,  the  period  of  youth 


208  Manual  of  Veterinary  Microbiology, 

should  be  preferred  for  vaccination.  The  immunity 
obtained  lasts  only  one  year,  but  this  term  is  sufficient 
for  the  needs  of  breeding  and  fattening.* 

Pneumo-enteritis  of  the  pig,  hog  cholera. 

Pneumo-enteritis  of  hogs  is  an  infectious  and  con- 
tagious disease  which  was  long  confounded  with 
rouget.  It  was  described,  in  the  first  place,  in  Amer- 
ica, by  Salmon  under  the  name  of  hog  cholera;  in 
France  it  has  been  investigated  by  Riestsch  and  Jo- 
bert,  and  Cornil  and  Chantemesse,  in  connection  with 
the  epizootics  at  Marseille  and  at  Gentilly ;  it  was 
studied  by  Selander  in  the  swine  of  Sweden  and 
Denmark. 

This  disease  chiefly  attacks  young  animals  and  is 
nearly  always  fatal.  It  manifests  itself  by  symptoms 
the  description  of  which  differs  somewhat  in  the  dif- 
ferent countries  in  which  it  has  been  observed. 

According  to  Salmon,  the  disease  maybe  acute  or 
chronic.  In  the  latter  case  inappetence  is  observed 
along  with  persistent  diarrhoea  and  slow  emaciation 
of  the  diseased  animals.  When  the  disease  is  acute 
the  diarrhoea  is  more  intense  and  sanguinolent.  In 
both  cases  the  intestine  is  much  altered,  principally 
the  large  intestine.  The  latter  presents  ulcerations 
and  considerable  thickening  of  its  mucosa  when  the 
disease  has  been  slow;  when  the  evolution  has  been 
rapid  the  lesions  assume  a  hemorrhagic  character  and 
aflfect  not  only  the  caecum  and  large  colon,  which  are 

*  [Lorenz  has  introduced  a  method  of  protective  inoculation  by 
the  use  of  the  blood-serum  of  swine  which  have  previously  been 
immunised  against  rouget.  {Centralblatt  fur  Bacteriologie,  xiii — 11, 
12.)-D.] 


Microbic  Diseases  Individually  Considered.      209 

much  injected  and  ulcerated,  but  also  the  spleen, 
liver,  kidneys,  and  mesenteric  glands.  Generally  the 
lungs  are  unaffected ;  nevertheless,  some  foci  of  hepa- 
tization may  be  noticed  in  the  last  stage  of  the  slow 
form  of  the  disease.  The  skin  of  the  neck  and  ab- 
domen, and  sometimes  of  the  whole  body,  is  red- 
dened. 

Intestinal  lesions,  therefore,  predominate  in  the  dis- 
ease studied  by  Salmon. 

The  disease  studied  in  France  is  characterized  by 
an  intense  fever  with  considerable  prostration  of  the 
affected  animals,  staggering  gait  and  sometimes  paral- 
ysis. An  intense  and  .fetid  serous  diarrhoea  soon 
supervenes;  this  is  often  preceded,  and  occasionally 
followed,  by  constipation  ;  at  the  same  time,  or  a  little 
later,  symptoms  of  pulmonary  trouble  become  evi- 
dent :  fitful  hoarse  cough,  accelerated  and  embarrassed 
respiration,  and  abundant  mucous  discharge  from  the 
nostrils. 

The  most  conspicuous  symptoms  vary  according  as 
the  intestinal  or  pulmonary  troubles  predominate.  In 
the  epizootic  at  Marseille  enteritis  was  constant  and 
the  pulmonary  lesions  incidental ;  on  the  contrary, 
broncho-pneumonia  was  the  dominant  feature  in  the 
epizootic  at  Gentilly.  MM.  Cornil  and  Chantemesse 
think  that  this  peculiarity  depends  upon  the  mode 
of  entrance  of  the  virus.  The  Gentilly  hogs  were 
contaminated  at  the  abattoir  by  inspiring  air  charged 
with  virulent  dust,  whilst  those  of  Marseille  con- 
tracted the  disease  by  ingestion  of  contaminated  food. 

In  the  course  of  the  disease  a  diffuse  inflammation 
often  develops  on  the  skin  of  the  lower  part  of  the 
18 


210  Manual  of  Veterinary  31icrohiology. 

abdomen,  on  the  perineum,  groins,  limbs,  and  at  the 
root  of  the  ears,  these  regions  then  taking  a  more  or 
less  pronounced  red  or  violet  color,  and  thus  tending 
to  increase  the  chances  of  confounding  it  with  rouget. 
These  cutaneous  changes,  however,  are  less  constant 
than  in  the  last  disease. 

Pneumo-enteritis  is  of  rather  long  duration :  twenty 
to  twenty-five  days  on  an  average,  never  less  than 
eight  to  ten  days ;  it  may  extend  to  five  or  six  weeks ; 
it  is  very  contagious,  and  few  hogs  which  have  been 
exposed  to  the  contagion  escape. 

In  very  rapid  cases  the  autopsy  shows,  beside  ec- 
chymoses  disseminated  through  the  connective  and 
inter-muscular  tissue,  peritoneum,  pleura,  pericardium, 
and  heart,  a  violent  inflammation  of  the  stomach  and 
intestines,  with  interstitial  hemorrhages  and  erosions 
or  ulcerations  at  Peyer's  patches;  the  mesenteric 
glands  are  voluminous  and  Infiltrated;  the  lungs  are 
normal  or  show  lobular  foci  of  hemorrhagic  congestion. 
When  the  evolution  of  the  disease  has  been  slow  the 
lesions  are  better  defined;  those  of  the  intestine, 
cfficum,  and  large  colon  are  especially  remarkable ; 
the  wall  of  these  organs  is  considerably  thickened  and 
indurated,  and  has  become  rigid.  The  swelling  and 
induration  chiefly  aflfect  the  Peyer's  patches  ;  these 
are  the  seat  of  a  necrotic  process  which  leads  to  the 
formation  of  grayish  colored  diphtheritic  exudates  and 
ulcerations  of  greater  or  less  extent,  both  in  area  and 
in  depth.  The  inflammation  sometimes  extends  to 
the  peritoneum. 

The  lungs  show  lesions  of  broncho-pneumonia  at  a 
more  or  less  advanced  stage;  pleurisy  is  also  occasion- 
ally present. 


Microhic  Diseases  Individually  Considered.       211 


«k  / 


The  mesenteric  and  bronchial  lymphatic  glands  are 
tumefied  and  sometimes  partly  caseous. 

31icrobe.—ThQ 
germ    of    pneumo-  Fig.  9. 

enteritis  belongs  to 
the  group  of  bac- 
teria showing  a  clear 
central  space,  that 
is,  those  which  take 
the  stain  better  at 
their  margins  than 
in  the  center.  It  is 
ovoid,  measures  1/i 
to  2/i  in  length  by 
0-4/^  to  0*6/i  in  thick- 
ness. It  is  motile, 
aerobic  and  facul-  Hog  cholera  bacilli  in  spleen  of  guinea 
tatively     anaerobic,    pis;  cover-glass  preparation.  X 1200.— D. 

It  does  not  form  spores. 

Action  of  physical  and  chemical  agents. — The  bacillus 
of  pneumo-enteritis  is  destroyed  by  a  temperature  of 
58°,  maintained  during  from  fifteen  or  twenty  minutes. 
It  preserves  its  vitality  in  spite  of  desiccation  for 
nearly  two  months.  It  vegetates  and  multiplies  in 
water  at  the  ordinary  temperature  of  summer ;  it  re- 
tains its  vitality  for  more  than  fifteen  days  in  sterilized 
water. 

Those  authors  who  have  studied  the  action  of  chem- 
ical agents  on  this  microbe  especially  recommend  for 
its  destruction  mineral  acids  and  sulfate  of  copper. 
MM.  Cornil  and  Chantemesse  recommend  the  follow- 
ing solution  for  the  disinfection  of  pens  and  other  in- 
fected objects  : 


212  Manual  of  Veterinary  3Iicrohiology. 

Water 100 

Carbolic  acid  ....         4 

Hydrochloric  acid       ...  2 

Cultures — Cultures  on  artificial  media  succeed  well 
at  temperatures  varj'ing  from  18°  to  45°, 

Bouillon  becomes  turbid  without  showing  any  spe- 
cial characters. 

Gelatin,  inoculated  in  superficial  lines,  shows  a 
raised  growth  of  white  or  bluish- white  appearance, 
with  irregular,  often  lace-like,  borders  ;  the  medium 
is  not  fluidified.  Inoculated  by  puncture  the  culture 
shows  itself  in  the  form  of  rounded  colonies  covered 
with  crystalline'  projections. 

The  culture  upon  potato  is  remarkable  for  its  clear 
brown  color,  which  gradually  becomes  deeper  with 
age. 

Sowings  ought  to  be  taken  from  the  parenchyma- 
tous organs :  liver,  lungs,  lymphatic  glands,  or  from 
the  blood. 

Schweinitz  has  isolated  from  cultures  a  toxic 
ptomaine  (sucholo-toxin)  and  a  special  albumin  (such- 
olo-albumin). 

Hesearch  and  coloration. — Salmon's  bacillus  readily 
takes  up  the  difterent  aniline  colors;  simple  methods 
of  staining  are  alone  applicable  :  hydro-alcoholic  solu- 
tions, Loifler's  blue,  etc.  The  methods  of  Gram  and 
Weigert,  and  Kiihne's  violet  completely  fail. 

Experimental  inoculations. — The  disease  is  inoculable 
to  the  mouse,  rabbit  and  guinea  pig.  The  pigeon 
takes  it  only  from  large  doses. 

In  the  mouse  the  microbe  assumes  larger  proportions 
than  in  the  pig,  and  multiplies  abundantly. 

The  rabbit,  inoculated  under  the  skin,  succumbs  in 


Microhic  J)iseases  Individually  Considered.      213 

from  three  to  eiglit  days  according  to  the  dose  in- 
oculated ;  the  lungs  are  gorged  with  blood,  the  intes- 
tines are  frequently  the  seat  of  a  violent  inflammation 
with  resulting  diarrhoea  ;  the  spleen  is  tumefied  and, 
alonff  with  the  liver,  often  shows  white  necrosed  foci. 
At  the  place  of  inoculation  a  creamy  mass  is  found, 
also  the  product  of  a  coagulative  necrosis. 

The  guinea  jng  dies  in  the  same  time,  and  with  the 
same  lesions,  as  the  rabbit.* 

The  pigeon  is  very  resistant  to  pneumo-enteritis.  It 
withstands  small  doses  inoculated  in  the  pectoral 
muscle  although  the  inoculated  point  becomes  the  seat 
of  a  sequestrum  similar  to  that  produced  by  chicken 
cholera.  Very  large  doses  kill  it  in  less  than  two 
days. 

The  chicken  is  refractory. 

The  pig  is  difficult  to  contaminate  by  hypodermic 
injection  ;  on  the  other  hand,  it  succumbs  ninety  times 
out  of  a  hundred  to  ingestion  of  virulent  products. 
It  contracts  the  same  disease  by  inhalation  of  dust 
containing  virulent  matters  held  in  suspension  in  the 
air,  and  also  by  intra-vascular  injection. 

Etiology  and  pathogeny. — The  cause  of  pneumo-en- 
teritis resides  in  the  bacillus  discovered  by  Salmon ; 
the  disease  generally  shows  itself  on  a  farm  in  conse- 
quence of  the  introduction  of  an  infected  hog ;  it  is 
transmitted  from  one  hog  to  another  by  the  ingestion 
of  food  or  drink  soiled  by  the  intestinal  dejections 
and  nasal  discharge  of  the  diseased  animals. 

*  [The  guinea  pig  appears  to  be  somewhat  less  susceptible  than 
the  rabbit,  and  rarely  shows  the  characteristic  necrotic  foci  found 
in  the  liver  in  the  latter  animal. — D.] 


214  Manual  of  Veterinary  Microbiology. 

MM.  Cornil  and  Chanteraesse  also  conclude  that  the 
germ  may  penetrate  by  the  respiratory  passages  and 
according  to  the  way  by  which  it  is  introduced,  the 
disease  will  act  more  particularly  upon  the  intestines 
or  upon  the  lungs. 

According  to  Salmon,  the  natural  virus  is  subject  to 
considerable  variations  of  activity,  and  this  explains 
the  sometimes  rapid  and  sometimes  slow  course  of  the 
disease. 

The  local  lesions  which  follow  its  penetration  assume 
the  general  character  of  an  inflammation  with  a  ten- 
dency to  early  mortification  ;  this  tendency  is  sufli- 
ciently  demonstrated  by  the  diphtheritic  exudates  and 
ulcerations  of  the  intestinal  mucous  membrane  and 
the  coagulative  necrosis,  under  the  form  of  caseous 
masses,  in  the  glands  of  diseased  hogs.  This  charac- 
ter also  shows  itself  in  the  mouse,  rabbit,  guinea  pig 
and  pigeon  which  have  been  subjected  to  exj)erimental 
inoculation. 

The  local  alterations  lead  to  emaciation  of  the  af- 
fected animals,  but  this  enfeeblement  is  complicated 
with  an  intoxication.  We  have  already  seen  that  a 
toxic  ptomaine  has  been  isolated  from  cultures  of 
pneumo-enteritis,  and  it  may  be  that  this  poison,  se- 
creted in  greater  abundance  by  very  virulent  germs,  is 
the  cause  of  the  vascular  changes  met  with  in  acute 
cases. 

The  resistance  of  the  bacteria  to  desiccation,  and 
the  facility  with  which  they  multiply  in  water  at  the 
ordinary  temperature,  are  conditions  which  favor  the 
persistence  of  the  disease  in  one  place  and  the  produc- 
tion of  new  centers  of  infection. 

Attenuation.     Vaccination. — Attempts  at  attenuation 


Microhic  Diseases  Indwidually  Considered.      215 

of  the  bacillus  of  pneumo-enteritis  have  been  made  by 
MM.  Cornil  and  Chantemesse.  They  had  recourse  to  the 
action  of  heat  upon  cultures.  A  culture  maintained 
at  43°  during  seventy-four  days  produces  only  a  local 
abscess  in  the  rabbit  but  is  still  regularly  toxic  for' the 
guinea  pig.  After  ninety  days  the  virus  no  more 
kills  guinea  pigs ;  they  contract  an  abscess  at  the 
point  of  inoculation,  whilst  rabbits  often  escape  even 
this  lesion.  The  virus  thus  attenuated  transmits  its 
special  virulence  to  its  descendants  and  confers,  on 
guinea  pigs  and  rabbits  which  have  received  it,  im- 
munity for  virus  which  has  been  heated  only  seventy- 
four  days ;  the  latter  acts  in  the  same  way  toward 
more  active  and  the  natural  virus.  It  is  therefore 
possible  to  vaccinate  the  rabbit  and  the  guinea  pig 
against  pneumo-enteritis.  Unfortunately  this  method 
of  prevention,  applied  to  the  pig,  has  not  given  the 
same  result,  and  a  process  of  vaccination  is  yet  to  be 
found  for  this  species. 

The  vaccine  of  rouget  does  not  vaccinate  hogs 
against  cholera,  a  circumstance  which  increases  the 
importance  of  the  differential  diagnosis. 

Schweinitz  has  succeeded  in  vaccinating-  the  sruinea 
pig  by  means  of  soluble  substances  which  he  has  iso- 
lated from  cultures.* 

*  [Billings  obtained  protection  against  this  disease  by  inocula- 
tion of  pigs  with  cultures  derived  from  mild  cases  of  the  natural 
disease.  A  certain  proportion  of  the  animals  die  from  the  inocu- 
lation. Neh.  Ag.  Exper.  Sta.,  Vol.  2,  No.  4.  Selander  (confirmed 
by  Metschnikoff)  found  that  cultures  of  the  Danish  swine-pest, 
increased  in  virulence  by  passage  through  pigeons,  produced  in 
the  blood  of  rabbits  very  active  toxines.  When  such  blood  was 
sterilized  at  57°  C.  and  injected  in  rabbits  it  conferred  a  solid  im- 
munity.   The  serum  of  rabbits  thus  vaccinated  was  also  iouud  to 


^16  Manual  of  Veterinary  Microbiology. 

Pneumo-enteritis  of  the  sheep. — M.  Giiltier  has  studied 
a  disease  in  tlie  sheep  to  which,  from  its  principal 
lesions,  he  has  given  the  name  of  pneumo-enteritis, 
and  which,  according  to  this  author^  is  caused  by  the 
germ  of  the  disease  of  the  pig  which  has  just  been 
described.  This  aftection  sometimes  occurs  in  an  epi- 
zootic form  in  sheep,  and  may  make  great  ravages 
in  aftected  flocks.  In  several  cases  the  disease  had 
originated  in  consequence  of  the  introduction  into  the 
sheep-folds  of  swine  recently  purchased  and  which 
had  contracted  pneumo-enteritis  in  the  market  pens. 
Once  established  in  sheep,  it  transmits  itself  with  great 
facility  from  sheep  to  sheep. 

The  general  symptoms  consist  in  lassitude  and  gen- 
eral loss  of  vigor  of  the  affected  animals,  w^ith  inappe- 
tence,  loss  of  rumination  and  the  appearance  of  a 
more  or  less  intense  fever.  These  symptoms  are  soon 
succeeded  by  bloating,  fetid  and  exhausting  diarrhoea, 
cough,  accelerated  respiration,  mucous  discharge  from 
the  nostrils  sometimes  streaked  with  blood,  and  the 
special  symptoms  of  a  broncho-pneumonia  or  of  a 
broncho-pleuro-pneumonia.  The  skin  and  the  visible 
mucous  membranes  take  a  more  or  less  vivid  red  color, 
sometimes  mixed  with  hemorrhagic  points.  In  preg- 
nant females  abortion  is  often  observed  although  the 
mother  does  not  necessarily  succumb  to  the  attacks  of 
the  disease. 

The  disease  may  show  various  degrees  of  intensity ; 
it  is  sometimes  very  severe  and  kills  in  a  few  hours,  or 
days,  sometimes  benign  and  passes  unperceived.  Con- 
possess  immunising  properties.  Annates  de  rinsl.  Pasteur,  1 890,  p. 
646.  These  results  are  not  obtained  with  the  American  disease. 
(Smith  &  Moore.)— I>.J 


Microbic  Diseases  Individually  Considered.      217 

valescence  from  the  severe  forms  is  always  prolonged. 
The  receptivity  of  sheep  diminishes  with  age ;  thus, 
the  disease  is  noticed  to  be  more  severe  and  more  fre- 
quently fatal  in  young  animals. 

The  bodies  rapidly  putrefy ;  the  subcutaneous  and 
intermuscular  connective  tissue  is  dotted  with  hemor- 
rhagic points,  sometimes  with  gelatinous  exudates. 
The  peritoneum,  pleura,  and  sometimes  the  peri- 
cardium may  be  the  seat  of  fibrinous  inflammations. 
The  mucous  membrane  of  the  fourth  stomach,  small 
and  large  intestine,  is  congested;  it  shows  extrava- 
sated  points  and  sometimes  erosions;  Peyer's  patches 
are  tumefied.  The  liver  is  also  hyper?emic  and  dotted 
with  petechias ;  sometimes  it  contains  abscesses  when 
the  disease  has  been  somewhat  prolonged.  There  are 
disseminated  lesions  of  broncho-pneumonia  with  in- 
filtration and  thickening  of  the  interlobular  connective 
tissue  septa.  The  mucous  membrane  of  the  bronchi 
and  of  the  trachea  is  reddened  and  thickened,  and  se- 
cretes an  abnormal  quantity  of  mucus.  When  the 
disease  has  developed  slowly,  caseous  foci  are  not  in- 
frequently found  in  the  lungs.  The  lymphatic  glands 
of  the  mesentery  and  of  the  root  of  the  lung  are  en- 
larged, congested  and  infiltrated. 

The  micro-organism  which  produces  this  disease  of 
the  sheep  is  identical,  according  to  M.  Galtier,  with 
that  of  pneumo-enteritis  of  the  pig.  This  author 
claims  to  have  succeeded  in  transmitting  this  last  dis- 
ease to  the  sheep  by  inoculation,  as  well  as  in  trans- 
mitting the  disease  of  the  sheep  to  the  rabbit,  guinea 
pig,  dog,  pig,  goat,  calf,  to  solipeds,  to  the  chicken  and 
to  the  pigeon.  In  the  goat  it  resembles  the  pleuro- 
19- 


218  Manual  of  Veterinary  31icrohiology . 

pneumonia  (bou-frida)  peculiar  to  this  species ;  in  soli- 
peds  it  gives  rise  to  symptoms  recalling  the  typhoid 
disease ;  finally,  it  would  explain  epizootic  abortion 
when  it  is  spontaneously  transmitted  to  cows. 

Transmission  is  readily  procured  by  hypodermic,  in- 
travenous and  iutra-pulmonary  injection,  less  easily  by 
the  digestive  canal.  The  virus  loses  its  virulence  by 
multiple  transfers  on  artificial  media  and  passages 
through  individuals  in  which  the  disease  develops 
slowly.  On  the  contrary,  its  virulence  increases  in 
organisms  very  susceptible  to  its  influence.  Thus,  ac- 
cording to  M.  Galtier,  the  pneumo-enteritis  of  the  pigs 
at  Gentilly  is  transmissible  to  sheep  (contrary  to  the 
assertion  of  M.  Nocard)  when  the  substance  inocu- 
lated is  taken  not  from  a  culture  but  from  a  diseased 
animal. 

The  natural  contagion  occurs  by  ingestion,  and  es- 
pecially by  inhalation,  of  virulent  products.  The  dis- 
ease is  also  transmitted  from  the  mother  to  the  foetus. 

According  to  the  researches  of  M.  Galtier,  which 
we  have  just  briefly  reviewed,  pneumo-enteritis,  which 
is  generally  considered  to  be  peculiar  to  the  pig,  ex- 
tends to  all  farm  animals,  especially  to  the  sheep, 
bovines  and  solipeds.  The  disease  being  transmitted 
to  the  foetus,  calves  coming  from  diseased  cows  which 
are  or  have  been  subject  to  coughing  are  born  with 
the  germ  of  the  disease  in  them  and  die  in  a  few  days 
with  the  lesions  of  broncho-pneumonia  and  enteritis 
(pneumo-enteritis  of  calves). 

Infectious  pneumonia  of  the  ing,  swine  plague. 

This  disease  of  swine  has  been  described  in  Ger- 
many under  the  name  Schweineseuche,  and  in  Amer- 


Microbic  Diseases  Individually  Considered.       219 

ica  under  that  of  Swine-plague.  It  is  an  infectious 
and  epizootic  disease  characterized  by  the  predomi- 
nance of  the  pulmonary  lesions.  These  consist  of 
broncho-pneumonic  foci  with  or  without  complications 
of  pleurisy,  enteritis,  etc.  The  lung  often  contains 
caseous  masses ;  sometimes  it  is  gangrenous.  The 
evolution  is  acute  or  chronic  ;  in  the  first  case  the 
duration  of  the  disease  is  from  three  to  nine  hours  on 
an  average. 

There  is  present,  in  the  pulmonary  lesions,  pleura, 
peritoneum  and  pericardium,  a  non-motile  microbe, 
ovoid,  from  l/u.  to  l-2tj.  long  by  0.6//  in  thickness,  stain- 
ing only  at  its  extremities. 

The  disease  is  inoculable  to  the  mouse,  rabbit, 
guinea  pig,  chicken  and  pigeon,  but  large  doses  are 
required  to  produce  fatal  results  in  the  last  three 
species. 

It  is  transmitted  from  one  hog  to  another  by  inhala- 
tion, probably  also  by  ingestion,  and  perhaps  by  acci- 
dental cutaneous  inoculation. 


220 


Manual  of  Veterinary  Microbiology. 


Diferential   diagnosis  of   rougct,  pneumo-enteritis,  and 
swine-plague  (peste-porcine.)^ 


ROUGET. 


Course   rapid:    2    to    5 
days. 


Attacks  especially  adult 
liogs. 

Gpneral  symptoms  pre- 
dominating'. 

Redness  more  extend- 
ed, more  constant. 

Congestive  lesions  o  f 
all  the  organs,  with  pe- 
techial extravasations 
and  exudative  inflamma- 
tions of  serous  mem- 
branes. 

In  very  slow  cases  the 
intestine  may  contain  ul- 
eerations  at  Peyer'.*; 
patches  as  in  pneumo-en- 
teritis. 


Bacilli  cylindrical,  non- 
motile,  stained  by  the 
Gram  and  Weigert  meth- 
ods. 


Especially  anaerobic. 

Inpculable  to  the  mouse, 
rabbit  and  pigeon,  but 
not  to  the  guinea  pig. 


Culture  in  gelatin  has 
the  appearance  of  a  test- 
tube  brush. 


PNEDMO- ENTERITIS. 

Course  slow  ;  20  to  25 
days,  never  less  than  8  to 
10  days. 

Attacks  especially  young 
pigs. 

Gastro-pulmonary  symp- 
toms predominating. 


Redness    less 
less  constant. 


extended, 


Inflammatory  lesions  of 
a  necrotic  character  in  the 
intestine  posterior  to  the 
ileo-coecal  valve,  and  in  the 
mesenteric  and  bronchial 
glands. 

When  the  disease  is  rapid 
the  intestinal  changes  may 
not  have  reached  their 
usual  stage  and  thus  may 
cause  the  disease  to  be  mis- 
taken for  rouget.  This  mis- 
take is  more  easily  made 
in  cases  in  which  tlie  pul- 
monary lesions  have  not 
had  tirue  to  develop. 

Bacteria  ovoid,  motile 
not  stained  by  the  Gram  or 
Weigert  metliods.  The  cen- 
ter stains  much  less  than 
the  periphery. 

Especially  aerobic. 

Inoculable  to  the  mouse, 
rabbit,  and  guinea  pig,  to 
the  pigeon  only  when  very 
large  doses  are  employed; 
not  to  the  chicken. 

Culture  has  the  form  of 
globules  covered  with  crys- 
talline asperities. 


SWINE  PLAGUE. 


Pulmonary  localiz 
tion  predominating. 


Broncho-pneumonia 
with  caseous  foci. 


Bacteria  ovoid,  non- 
motile,  staining  only 
at  their  extremities. 


Inoculable  to  the 
mouse  and  to  the  rab- 
bit, and  wlien  large 
doses  are  employed  to 
the  guinea  pig,  pigeon 
and  chicken. 


■■■■■  [From  the  lack  of  distinctive  names  for  the  various  infectious 
diseases  of  swine  which  have  been  described  in  different  coun- 
tries, the  morphological  and  biological  similarity  of  their  germs, 
and  the  absence  of  any  post-mortem  lesions  which  are  absolutely 
characteristic,  there  still  exists  considerable  confusion  as  to  their 


Microbic  Diseases  hidividually  Considered.      221 

Tuherculosis. 

Tuberculosis  is  a  disease  too  well  known  to  require 
a  description  of  its  symptoms  and  lesions  in  this 
place.  We  will  consider  it  only  from  the  special  point 
of  view  of  its  bacteriology. 

The  disease  produces  its  greatest  ravages  in  the  hu- 
man species,  and  then,  with  a  frequency  decreasing  in 
the  order  in  which  they  are  named,  it  attacks  the 
bovine  species,  the  pig,  horse,  dog,  and  cat.  Fowls 
also  are  decimated  by  this  terrible  scourge.  The 
question  as  to  the  identity  of  human  and  avian  tuber- 
culosis has  been  much  discussed  and  is  still  in  dis- 
pute. 

The  distribution  of  the  specific  alterations  is  some- 
what difierent  in  the  difierent  species. 

In  cattle  they  are  most  frequently  found  in  the 
lungs,  pleura,  and  thoracic  glands,  but  are  also  com- 
mon in  the  intestines,  peritoneum,  liver,  kidneys, 
mammae,  and  the  corresponding  lymphatic  glands ; 
they  have  also  been  met  with  in  the  meninges,  inter- 
identity.  The  names  given  in  each  of  the  lists  below  seem  to  re- 
fer to  the  same  disease  : 

I.  Rouget,  in  France;  rothlauf,  in  Germany;  swine  erysipelas, 
in  England  (cases  described  by  McFadyean,  Jour.  Comp.  Path., 
Vol.  IV,  Part  4). 

II.  Pneumo-enteritis  (Klein),  swine  fever,  in  England  ;  svinpest 
(Selander),.in  Denmark  ;  hog  cholera  (Salmon  and  Smith),  swine 
plague  (Billings),  in  America. 

III.  Schweineseuche,  in  Germany;  swine  plague  (Smith),  in 
America  (uncertain). 

The  germ  of  the  French  disease  of  hogs  described  as  pneumo- 
enteritis,  as  well  as  that  of  Galtier,  has  not  been  identified  with 
that  of  either  of  the  diseases  included  under  lists  II  and  III. — D.] 


222  Manual  of  Veterinary  Microbiology. 

muscular  counective  tissue,  bones,  bone  marrow,  and 
the  articulations.  The  disease  is  especially  frequent 
in  adult  animals;  when  it  exists  in  the  calf  it  is  lo- 
cated nearly  always  in  the  abdominal  viscera,  and 
more  especially  in  the  liver  when  the  afieetion  is  con- 
genital ;  but  it  can  quickly  extend  to  the  thoracic  or- 
gans. We  have  had  the  opportunity  of  establishing 
this  extension  to  an  excessive  degree  in  the  viscera 
coming  from  the  abattoir  of  Brussels,  the  lungs  and 
bronchial  glands  showing  a  generalization  of  miliary 
tubercles.  In  two  cases  of  intra-uterine  infection  ob- 
served by  MM.  Malvoz  and  Brouwier  the  lung  was 
exempt  from  lesions,  these  occupying  the  liver,  hepatic, 
and  bronchial  glands. 

The  pig,  although  very  susceptible  to  the  experi- 
mental disease,  appears  to  be  rarely  affected  with  tu- 
berculosis; here  it  is  the  pulmonary  form  that  pre- 
dominates. M.  Moule  has  communicated  a  case  in 
which  he  observed  extension  to  the  pleura,  ribs,  and 
muscles.  Microscopical  and  bacteriological  researches 
have  enabled  us  to  connect  with  tuberculosis  those 
scrofulous  alterations  of  the  cervical  glands  which  are 
occasionally  observed  in  the  pig.  According  to  M. 
N'ocard,  the  disease  in  this  species  often  develops  with 
great  rapidity  and  passes  unperceived ;  in  the  chronic 
forms  the  bacilli  are  rare  and  seem  to  have  lost  part 
of  their  virulence ;  inoculated  to  guinea  pigs  they  pro- 
duce a  disease  of  slow  course ;  but  the  period  of  in- 
cubation becomes  shortened  again  when  these  bacilli 
are  inoculated  from  the  lirst  guinea  pig  to  others  in 
series.  This  property  belongs  also  to  the  lesions  of 
human  scrofula. 

In  the  horse  two  forms  of  tuberculosis  exist ;  the 


Microbic  Diseases  Individually  Considered.      223 

abdominal  form,  the  most  frequent,  is  characterized 
by  confluent  lesions  in  the  spleen,  mesenteric  glands, 
liver,  and  intestines;  in  the  thoracic  form  the  changes 
occur  chiefly  in  the  lungs ;  the  latter  also  develop,  but 
more  slowly,  as  a  sequel  to  abdominal  tuberculosis. 
According  .to  M.  ISTocard,  who  gave  us  our  first  in- 
formation upon  tuberculosis  of  the  horse,  this  disease 
is  often  accompanied  with  a  polyuria  of  remarkable 
intensity. 

In  the  dog  the  disease  also  occurs  under  the  two 
forms  observed  in  the  horse.  A  considerable  number 
of  cases  of  tuberculosis  in  this  species  have  already 
been  communicated.  We  ourselves  have  seen  two 
cases.  In  the  first  the  liver  was  enlarged  and  infil- 
trated with  a  neoplastic  tissue  of  a  grayish  color,  which, 
under  the  microscope,  was  resolved  into  miliary  tuber- 
cles destitute  of  giant  cells.  The  hepatic  and  mesen- 
teric glands  were  much  tumefied,  and  partly  caseous. 
The  lung  contained  two  nodules  of  the  size  of  a  pea. 
The  second  dog  showed  generalized  tuberculosis  of 
both  lungs,  and  of  the  bronchial  glands. 

The  ape  is  very  susceptible  to  the  disease,  and  very 
readily  contracts  it  in  our  climate. 

In  fowls  the  abdominal  viscera  are  most  affected, 
and  this  often  to  an  excessive  degree.  In  this  species 
the  liver  seems  to  be  the  place  of  predilection  for  the 
tubercles  ;  sometimes  the  latter  are  absent,  only  a  con- 
siderable enlargement  with  degeneration  of  this  or- 
gan being  observed,  but  the  spleen,  intestines,  and 
peritoneum  may,  at  the  same  time,  be  studded  with 
lesions.     The  lung  is  rarely  affected. 

Microbe. — The  efiicient  cause  of  tuberculosis  resides 
in  the  bacillus  of  Koch.     This  shows  itself  under  the 


OF   THE 

UNIVERSITY 


S'F  m  icfMj»i\K 


224  3Ianual  of  Veterinary  Microbiology. 

form  of  a  homogeneous  rod,  or  more  frequently  com- 
posed of  granules  arranged  in  linear  series.  It  is 
straight  or  bent  in  the  form  of  an  arc,  sometimes 
S-shaped;  it  measures  2/^  to  6/i  in  length  by  0-3/i  to 
0-5;^  in  thickness.  The  rod  is  uniform  in  size  through- 
out its  extent. 

According  to  Cornil  and  Bab^s  the  granular  appear- 
ance is  especially  observed  in  bacilli  long  abandoned 
to  the  air ;  these  authors  have  demonstrated  the  same 
granules  in  bacilli  coming  from  cultures  and  they  re- 
gard them  as  spores. 

A  certain  number  of  the  bacilli  are 
observed  to  become  considerably  elon- 
gated and  to  swell  at  one  of  their  ex- 
tremities; we  have  often  seen  these 
abnormal  forms  in  bouillon  cultures 
of  avian  tuberculosis. 

Action  of  -physical  and  chemical  agents. — Tubercle 
bacilli  are  killed  by  a  temperature  of  70°,  maintained 
during  ten  minutes  (Yersin).  According  to  M.  Gal- 
tier,  heating  at  71°  during  ten  minutes  does  not  suffice 
to  sterilize  tuberculous  matter.  Moist  heat  at  100° 
sterilizes  it  with  certainty  in  a  few  minutes,  but  this 
is  not  the  case  when  the  virulent  substance  is  in  the 
dry  state,  for  the  dried  spores  withstand  100°. 

The  tubercle  bacillus  withstands  freezing,  putrefac- 
tion and  desiccation.  This  last  operation,  when  it 
occurs  at  temperatures  near  to  30°,  is,  indeed,  an  im- 
portant means  of  preserving  it.  The  bacillus  retains 
its  vitality  for  a  considerable  time  in  sterilized  water 
(seventy  days). 

According  to  Yersin,  carbolic  acid,  at  5  per  cent, 
kills  the  bacillus  in  half  a  minute  ;  sublimate,  at  1  to 


Fig. 

10. 

.yJ\      yy 

/  —  / 

Tubercle 

bacilli, 

(M.  an 

dL.) 

Microbic  Diseases  Indicidualbj  Considered.       225 

1,000,  ill  ton  minutes ;  absolute  alcohol  in  five  minutes; 
but  contact  with  these  agents  must  be  much  more  pro- 
longed in  the  case  of  tuberculous  substances,  sputa, 
etc.  Hence,  for  the  destruction  of  the  virulence  of 
these  substances,  moist  heat  should  be  preferred. 

The  tubercle  bacillus  resists  the  action  of  the  gastric 
juice. 

Cultures. — Vegetation  of  the  bacillus  on  artificial 
media  is  not  easily  obtained  ;  the  operation,  however, 
is  only  delicate  for  the  first  generation.  The  culture 
media  most  favorable  for  this  bacillus  are  those  which 
contain  an  addition  of  peptone,  glycerin,  and  even  of 
glucose,  in  proper  proportions.  The  incubating  oven 
should  be  kept  at  a  temperature  in  the  neighborhood 
of  39°,  that  temperature  being  best  suited  for  the 
growth  of  the  bacillus ;  multiplication  is  impeded  by 
slight  deviation  from  this  temperature,  and  ceases 
altogether  at  about  35°.  As  the  germ  is  aerobic,  the 
culture  medium  should  also  be  freely  exposed  to  the 
air.  The  sowing  should  be  taken  from  virulent 
products  from  young  tuberculous  animals  in  which 
the  evolution  is  rapid,  and  should  be  implanted  at 
once  upon  serum ;  it  is  transferred  several  times  upon 
this  medium  before  trusting  it  to  others. 

On  serum,  at  the  end  of  twelve  to  fifteen  days, 
small,  round,  whitish  grains  appear,  and  slowly  in- 
crease in  size ;  these  grains  are  slightly  raised,  dry, 
and  scaly  in  appearance ;  their  growth  is  very  limited 
in  the  first  cultures  and  they  become  confluent  only 
after  the  fourth  or  fifth  generation  ;  vegetation  is  then 
more  rapid  and  the  whole  surface  of  the  serum  be- 
comes covered  with  a  thin,  dry  film,  studded  with  ver- 
rucose  prominences. 


226  Manual  of  Veterinary  3jicrohiology. 

Sowing  of  tuberculosis  of  mammals  directly  upon 
agar  failed  of  results  in  the  hands  of  MM.  Straus  and 
Gamaleia.  and  even  transference  of  serum  cultures 
on  to  agar  only  succeeded  well  after  four  or  five  pas- 
sages on  the  serum. 

The  bacillus,  therefore,  requires  to  become  accli- 
mated on  an  artificial  medium  in  order  to  obtain  a 
vigorous  growth.  If  it  is  then  transferred  to  animals 
it  vegetates  satisfactorily. 

The  appearance  of  cultures  on  agar  resembles  that 
of  serum  cultures. 

In  the  case  of  avian  tuberculosis  much  richer  cul- 
tures are  obtained  directly  upon  serum.  These  cul- 
tures begin  by  rounded,  whitish  spots,  waxy  and 
moist,  which  after  a  few  transfers  produce  a  continu- 
ous layer  of  the  same  appearance,  thus  contrasting 
with  the  meager  and  dry  film  of  human  tuberculosis 
(Straus  and  Gamaleia).  Cultures  on  agar  and  on 
bouillon  are  also  more  readily  obtained  and  more 
abundant  than  in  the  case  of  human  tuberculosis. 

In  bouillons,  after  a  few  days,  small  flakes  appear 
which  gradually  increase  in  size  and  fiill  to  the  bot- 
tom of  the  liquid  without  becoming  dissociated  ;  they 
break  up  into  finer  particles  only  when  the  vessel  is 
shaken. 

The  tubercle  bacillus  also  vegetates  on  potato,  al- 
though this  is  not  a  very  favorable  medium  for  its 
growth. 

Research  and  coloration. — Koch's  bacillus  fixes  color- 
ing matters  with  difficulty  and  hence  requires  pro- 
longed exposure.  In  order  to  abbreviate  the  opera- 
tion recourse  is  often  had  to  heat.  The  coloration, 
however,  if  slowly  obtained,  is  persistent  even  against 


Microhic  Diseases  Individually  Considered.       227 

the  action  of  strong  acids — nitric  and  sulphuric  ;  upon 
this  property  are  based  the  diiferent  methods  of  double 
staining  which  we  will  now  describe.  This  property 
is  also  possessed  by  the  bacillus  of  leprosy. 

1.  Ehrlich's  method. 

The  staining  fluid  is  composed  as  follows : 

Aniline  water  (1)  .         .         .         .         9  cub.  cent. 
Absolute  alcohol      .         .         .         .     1  cub.  cent. 

•  Concentrated  alcoholic  solution  of 
fuchsin,  methyl  violet,  or  gentian 
violet    .         .         .         .         .         .1  cub.  cent. 

Cover  glasses  remain  in  this  solution  half  an  hour 
at  least,  sections  twenty-four  hours. 

Decoloration  is  obtained  by  a  dilution  of  nitric 
acid — 1  part  nitric  acid  in  5  parts  distilled  water  or  in 
10  parts  alcohol.  Cover  glasses  or  sections  should  re- 
main in  the  decolorizing  fluid  only  from  half  a  min- 
ute to  a  minute.  They  are  then  washed  in  distilled 
water  and  mounted.  If  it  is  desired  to  stain  the 
background  of  the  specimen  so  as  to  render  the  color 
of  the  bacilli  more  distinct,  the  preparations,  after 
coming  from  the  distilled  water,  are  placed  in  a  hydro- 
alcoholic  solution  of  methylene  blue  if  fuchsin  has 
been  the  first  stain,  or  in  eosin,  safranin,  bismark  brown, 
etc.,  if  the  bacilli  have  been  stained  violet ;  then  they 
are  mounted. 

The  time  required  by  this  method  may  be  abridged 
by  raising  the   temperature   of  the  staining  fluid  to 

(1)  Aniline  water  is  made  in  the  following  manner:  A  drop  of 
aniline  oil  is  added  to  a  few  cubic  centimeters  of  distilled  water  in  a 
test  tube  ;  the  tube  is  vigorously  shaken  in  order  to  dissolve  the 
oil,  and  a  few  drops  of  absolute  alcohol  added  to  complete  this 
solution. 


"228  Manual  of  Veterinary  Microbiology. 

near  the  boiling  point  before  the  introduction  of  the 
specimens  to  be  stained.  The  necessary  staining  is 
thus  obtained  in  a  few  minutes. 

2.  Lubimoff's  method. 

The  staining  fluid  is  composed  of-. 

Water  ....         20  cub.  cent. 

Boric  acid         .         .         .  0-5  grams. 

Absolute  alcohol  .        .        15  cub.  cent. 

Fuchsin    .         .         .         .  0-5  grams. 

This  fluid  keeps  indefinitely. 

To  stain  the  bacilli  upon  the  cover  glass  a  few  drops 
of  the  solution  are  deposited  upon  its  surface  and 
heated  for  two  minutes  over  a  spirit  lamp ;  the 
preparation  is  then  rapidly  decolorized  in  sulfuric 
acid  diluted  to  1  to  5,  then  rinsed  with  alcohol  and 
immersed  in  a  concentrated  alcoholic  solution  of 
methylene  blue ;  it  is  then  washed  with  water,  dried 
and  mounted  in  balsam. 

Sections  of  tubercular  tissue  are  left  during  one  or 
two  minutes  in  the  staining  fluid,  previously  heated 
to  near  the  boiling  point,  then  passed  for  a  few  seconds 
into  alcohol  and  thence,  for  one  to  two  minutes,  into 
a  1  to  5  dilution  of  sulfuric  acid,  again  into  alcohol 
and,  finally,  for  one  minute,  into  a  hydro-alcoholic  so- 
lution of  methylene  blue.  Dehydration  is  accom- 
plished by  passing  the  sections  through  absolute  alco- 
hol and  xylol  and  they  are  then  mounted  in  balsam. 

3.  Ziehl-Neelsen  incthod. 

The  staining  fluid  is  composed  by  mixing : 
Fuchsin      .         .         •         .         .  1  gram. 

Absolute  alcohol.  ....       10  grams. 
Five  per  cent  aqueous  solution  of  car- 
bolic acid.  ....     100  grams. 


Microbic  Diseases  Individually  Considered.       229 

The  different  steps  of  the  operation  are  exactly  the 
same  as  in  Lubimoff 's  method. 

4.  Herman's  method. 

The  staining  fluid  is  made  extemporaneously  and 
from  two  solutions : 

(1)  A  one-per-cent  aqueous  solution  of  carbonate 
of  ammonia ; 

(2)  An  alcoholic  solution  of  methyl  violet  6  B  (1  of 
the  violet  to  30  of  95  per  cent  alcohol). 

A  few  drops  of  the  second  solution  are  added  to 
several  cubic  centimeters  of  the  first  until  the  mixture 
obtains  a  deep  violet  color  and  this  is  brought  to  a  tem- 
perature approaching  ebullition.  The  cover  glasses  or 
sections  are  left  in  the  stain  from  one  to  two  minutes, 
then  placed  for  from  two  to  three  seconds  in  nitric 
acid  diluted  1  to  4  for  sections  and  1  to  10  for  cover 
glasses  ;  after  passing  through  the  dehydrating  fluids 
they  are  ready  for  mounting. 

Double  staining  may  be  obtained  by  immersing  the 
preparations,  after  passing  through  the  nitric  acid  and 
the  alcohol,  in  an  aqueous  or  alcoholic  solution  of  eosin. 

5.  Kitfs  inethod. 

This  requires  two   fluids  both  of  which  preserve 
themselves  indefinitely  :  * 
(1)  Aniline  water,      ....      100  grama. 
1  per  cent  solution  of  caustic  soda,        1      " 


Fuchsin,             .         .         .         . 

4  to  5      " 

(2)  Alcohol,        .... 

50  grams 

Water,       .         •         .         .         . 

.   30      " 

Nitric  acid,    .... 

20      " 

Methylene  blue  to  saturation. 

®  [The  aniline-containing  solutions  will  generally  be  found  unfit 
for  use  after  one  or  two  weeks.— D.] 


230  Manual  of  Veterinary  Microbiology. 

The  preparations,  cover  glasses  or  sections,  are  left 
for  from  two  to  five  minutes  in  the  fuchsin  solution 
heated  as  in  the  preceding  methods,  and  then  trans- 
ferred to  the  second  solution,  in  which  they  remain 
one  to  two  minutes.  During  this  last  period  all  the 
elements  other  than  the  Koch  bacilli  are  decolorized 
under  the  influence  of  the  nitric  acid,  but,  at  the  same 
time,  fix  the  blue  so  that  double  staining  is  combined 
with  decoloration. 

The  preparations  are  washed,  dehydrated,  and 
mounted. 

All  these  methods  have  the  same  value  in  so  far  as 
the  coloration  which  they  give  is  concerned.  In  prac- 
tice, however,  those  solutions  may  be  recommended 
which  are  of  longest  preservation,  and  which  require 
the  fewest  manipulations.  The  method  of  Kitt  es- 
pecially fulfills  these  two  conditions.* 

In  the  living  subject  about  the  only  materials  available 
for  examination  are  fluid  products,  such  as  nasal  dis- 
charge, milk  or  pus.  In  examining  milk  for  tubercle 
bacilli  the  cover  glass,  after  drying  and  before  staining, 
should  be  freed  from  fatty  matters  by  immersion  in  a 
mixture  of  absolute  alcohol  and  ether,  or  in  chloro- 
form. If  a  deposit  is  formed  at  the  bottom  of  the 
liquid  this  will  furnish  the  best  material  for  examina- 
tion. 

Very  often  the  Koch  bacillus  has  to  be  sought  for 
in  cadaveric  products.  In  this  case  the  investigations 
will  be  directed  to  the  tubercular  lesions  or  those  sus- 

*  [Of  the  two  methods  most  frequently  employed — Ehrlich's 
and  Ziehl's— the  latter,  on  account  of  the  greater  preservation 
of  the  staining  fluid,  is  often  the  most  convenient,  whilst  the 
former  gives  a  more  brilliant  color  to  the  bacilli.  — B.] 


Microbic  Diseases  Individually  Considered.       231 

pected  from  their  physical  characters  to  be  of  a  tuber- 
cular nature. 

In  the  case  of  young,  gray  tubercles  it  suffices  to 
spread  upon  a  cover  glass  the  product  obtained  by 
scraping  their  cut  surface :  the  bacilli  are  here  uni- 
formly distributed.  But  when  the  tubercles  are  al- 
ready caseated  the  caseous  matter  frequently  contains 
but  few  bacilli  except  in  birds,  where,  on  the  contrary, 
they  are  very  numerous ;  this  substance  is  first  re- 
moved and  the  bacilli  sought  for  in  the  wall  of  the 
caseous  tubercle.  The  same  method  may  be  employed 
for  cavities  although  these  often  contain  a  liquid  very 
rich  in  bacilli. 

Experimental  inoculations. — Tuberculosis  is  inocula- 
ble  to  the  horse,  ass,  ox,  sheep,  pig,  dog,  cat,  rabbit, 
guinea  pig,  and  to  fowls. 

Subcutaneous  inoculation  is  without  effect  in  the 
horse,  ass,  sheep,  pig,  dog,  cat,  and  chicken. 

Ingestion  of  virulent  substances  produces  the  dis- 
ease, but  not  in  all  cases,  in  the  horse,  sheep,  pig,  dog, 
and  cat.  Cattle  are  easily  tuberculized  in  this  way. 
The  chicken  remains  unaffected  when  sputa  or  tuber- 
cular products  of  mammals  are  mixed  with  its  food. 

Intravenous  injection  gives  much  surer  results. 
Except  in  the  case  of  birds  it  is  almost  invariably  fol- 
lowed by  a  generalized  tuberculosis  of  the  lung  with 
possible  extension  to  other  organs.  In  the  ass  the 
experiments  of  M.  Chauveau  have  shown  that  these  pul- 
monary granula  heal  spontaneously  after  a  few  weeks. 
Fowls  do  not  usually  contract  the  tuberculosis  of 
mammals  by  way  of  the  circulation.  Thus,  MM. 
Cadiot,  Gilbert,  and  Roger  have  recently  announced 
that  out  of  forty  pullets  inoculated  by  them  either  in 


232  Manual  of  Veterinary  3Iierohiology. 

the  veins  or  in  the  peritoneum,  five  only  developed 
tubercular  lesions. 

The  goat  forms  a  specially  unfavorable  field  for  the 
development  of  tuberculosis  and  was  long  considered 
to  be  absolutely  refractory  to  the  inoculated  as  well  as 
to  the  spontaneous  disease.  M.  Nocard  has  recently 
described  the  evolution  of  the  disease  in  a  goat  inocu- 
lated in  the  jugular  five  years  before,  and  which  at 
last  had  become  afiected  w4th  mange ;  M.  Colin  has 
also  produced  the  disease  in  a  goat  inoculated  under 
the  skin  with  particles  from  the  ox. 

The  laboratory  animals — guinea  pigs  and  rabbits — 
are  very  susceptible  to  the  disease.  The  guinea  pig 
is  endowed  with  a  quite  special  receptivity  which 
makes  it  the  reagent  par  excellence  for  tuberculosis. 

Subcutaneous  inoculation  on  the  internal  face  of 
the  thigh  in  the  guinea  pig  is  followed  by  a  local  ab- 
scess when  the  inoculated  substance  contains  at  the 
same  time  pyogenic  germs,  or  only  by  a  few  yellowish 
granulations  if  it  is  pure  ;  at  the  end  of  ten  to  fifteen 
days  there  supervenes  an  engorgement,  sometimes  an 
abscess,  of  the  superficial  inguinal  lymphatic  glands; 
the  sublumbar  glands  of  the  corresponding  side  are 
invaded  about  the  twentieth  day  ;  between  the  twenty- 
second  and  twenty-fifth  days  tubercles  appear  in  the 
spleen  and  retro-hepatic  glands  ;  the  lungs,  liver,  and 
the  other  lymphatic  glands  are  attacked  later.  The 
disease  lasts  about  two  months.  When  the  inocula- 
tion has  been  made  at  the  ear  the  invasion  takes  place 
by  the  anterior  lymphatics,  and  the  lungs  are  attacked 
before  the  abdominal  viscera. 

Subcutaneous  inoculation  on  the  internal  face  of 
the  thigh  or  at  the  ear,  in  the  rabbit,  does  not  give 


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Microbic  Diseases  Individually  Considered.     233 

rise  to  engorgement  of  the  corresponding  lym- 
phatic glands.  The  local  lesion  is  less  pronounced 
than  in  the  guinea  pig,  and  generalization,  less  con- 
stant, occurs  through  the  intermediation  of  the  blood  ; 
the  changes,  here,  are  found  chiefly  in  the  lung. 
With  bovine  tuberculosis,  in  certain  cases  in  the  rab- 
bit, M.  Arloing  has  seen  the  development  of  glandular 
lesions  resembling  those  of  the  guinea  pig. 

lutra-peritoneal  inoculation  in  the  rabbit  and  guinea 
pig  determines  tubercular  lesions  of  the  peritoneum, 
epiploic  glands,  liver,  and  spleen.  The  duration  of 
the  disease  is  always  shorter  than  by  the  subcutaneous 
method. 

Intra-vascular  inoculation  produces  a  generalized 
tuberculosis,  but  death  is  so  rapid  (fifteen  to  twenty 
days)  that  the  specific  lesions  are  not  visible  to  the 
naked  eye.  The  bacilli  are  disseminated  throughout  all 
the  parenchymatous  organs  (septictemic  type,  Yersin). 

According  to  Straus  and  Gamaleia  this  tuberculous 
septicfemia  is  obtained  only  with  the  cultures  of  avian 
tuberculosis. 

Diagnosis  of  doubffid  cases  in  cattle. — In  cattle  the 
-diagnosis  of  tuberculosis  by  means  of  the  clinical 
s^'mptoms  is  often  difficult.  ISTot  to  speak  of  abdom- 
inal forms  which  are  still  more  difficult  of  recognition, 
the  discharge  from  the  nostrils  is  often  absent  in  pul- 
monarv  tuberculosis,  and  the  search  for  the  essential 
element — the  bacillus — consequently  denied  to  us. 

M.  ISTocard,  basing  himself  on  the  fact  that  cattle 
are  accustomed  to  swallow  their  expectorations,  ad- 
vises looking  for  the  bacillus  in  the  pharyngeal  mu- 
cus; this  can  be  obtained   by  scraping  the   mucous 
20 


234  Manual  of  Veterinary  3Hcrohlolo<jy. 

membrane  of  the  throat  with  a  spatula.  Cagny  pro- 
poses, in  order  to  increase  the  bronchial  secretion,  the 
injection  under  the  skin  of  ten  to  twenty  centigrams 
of  veratrine. 

Poels  has  resorted,  in  the  absence  of  discharsre,  to 
tracheotomy  and  the  examination  of  the  tracheal 
macus. 

The  rarity  of  tubercular  lesions  of  Demour  and 
Decemet's  membrane  tends  to  refute  the  assertion 
of  M.  Mandereau  as  to  the  constant  presence  of  the 
bacillus  in  the  aqueous  humor  of  tuberculous  animals, 
and  this  assertion,  which  promised  an  easy  diagnosis 
of  the  disease,  has  quickly  been  contradicted  by  Le- 
clainche  and  GrefRer,  whose  investigations  on  twenty 
animals  which  were  certainly  affected  always  gave 
negative  results. 

M.  Peuch,  having  placed  an  irritating  seton  in  a 
tuberculous  cow,  found,  by  inoculating  the  pus  of  the 
seton  to  guinea  pigs,  that  the  bacilli  passed  into  the 
pus  from  the  eighth  to  the  fourteenth  day.  He  there- 
fore recommends  the  application  of  such  an  exudatory, 
and  subsequent  inoculation  in  order  to  remove  the 
uncertainty  of  the  diagnosis. 

If  the  presence  of  the  bacillus  in  the  expectoration 
enables  us  to  affirm  the  existence  of  the  disease,  its 
absence  does  not  authorize  us  in  positively  affirming 
that  it  does  not  exist.  Sometimes  it  is  necessary  to 
resort  to  inoculation  of  expectorated  products,  and 
the  same  precaution  should  be  observed  when  dealing 
with  milk,  etc.  Under  such  circumstances  we  have 
recourse  preferably  to  the  guinea  pig,  and  only  in  de- 
fault of  this  animal,  to  the  rabbit. 

When  we  possess  pure  products — cultures  or  young 


Microhic  Diseases  Individually  Considered.      235 

tubercles  collected  in  a  state  of  purity  and  reduced  to 
pulp — the  inoculation  can  with  advantage  be  made 
into  the  peritoneal  cavity,  thus  obtaining  a  more 
rapid  evolution ;  when  we  have  only  at  our  disposal 
virulent  matters  contaminated  with  other  germs,  such 
as  pus  or  nasal  discharge,  we  must  content  ourselves 
with  subcutaneous  inoculation.  A  region  should  be 
preferred  in  which  the  lymph  glands  are  easily  ex- 
plorable  in  order  that  the  progress  of  the  lesions  may 
be  followed.  In  default  of  this  exploration  the  ema- 
ciation of  the  subject  after  the  time  specified  above 
will  enable  us  to  affirm,  before  the  autopsy,  that  the 
inoculation  has  been  successful. 

Tiibercidin. — Another  means  of  diagnosis  consists  in 
testing  with  Koch's  lymph  or  tuberculin. 

Cultures  of  the  tubercle  bacillus  contain  a  soluble 
product  discovered  by  Koch  which  possesses  a  very 
remarkable  property.  This  substance  is  without  efiect 
on  healthy  individuals,  whilst  it  is  toxic  for  the  tuber- 
culous. The  name  tuberculin  has  been  given  to  a 
glycerin  extract  of  cultures  which  contain  this  active 
agent.  Since  his  first  discoveries  Koch  has  simplified 
the  process  by  which  it  is  prepared.  Large  cultures 
in  veal  bouillon,  to  which  has  been  added  one  per  cent 
of  peptone  and  from  four  to  five  per  cent  of  glycerin, 
are  reduced  to  one-tenth  their  volume  at  a  tempera- 
ture of  about  100°,  then  filtered  through  porcelain  so 
as  to  remove  all  the  microbes.  The  tuberculin  thus 
obtained  contains  enough  glycerin  for  its  own  preser- 
vation. The  product  has  not  a  stable  composition. 
Koch  recommends  testing  its  activity  on  tuberculous 
guinea  pigs.  According  to  this  author,  a  good  speci- 
men of  tuberculin,  in  the  dose  of  one  centigram,  kills 


236  Manual  of  Veterinary  Microbiology. 

a  guinea  pig  wliich  lias  been  inoculated  eiglit  to  ten 
weeks  before ;  it  requires  twenty  to  thirty  centigrams, 
sometimes  even  as  much  as  fifty  centigrams,  to  kill  a 
guinea  pig  inoculated  four  to  five  weeks  before.  The 
guinea  pigs  die  in  six  to  thirty  hours,  according  to 
the  extent  of  the  tubercular  process. 

Tuberculin,  after  twenty-four  hours'  treatment  with 
two  to  three  volumes  of  alcohol,  yields  up  its  active 
substance  in  the  form  of  a  precipitate  of  an  albuminoid 
nature. 

Tuberculin  causes  in  tuberculous  subjects  : 

1st.  A  more  or  less  intense  febrile  reaction  which 
supervenes  after  several  hours,  usually  from  the  tenth 
to  the  twentieth ; 

2d.  A  quite  remarkable  inflammatory  reaction 
around  the  tuberculous  foci.  This  substance  is  there- 
fore pyretogenic  and  phlogogenic,  but  as  the  first  of 
these  actions  produces  its  effects  indirectly  it  is  some- 
what delayed.  According  to  Gamaleia,  the  mode  of 
action  of  tuberculin  is  somewhat  as  follows :  It  pos- 
sesses properties  which  are  especially  toxic  for  the  ele- 
ments of  the  tubercle,  cause  them  to  undergo  necro- 
biosis in  the  same  way  as  the  secretions  of  the  bacillus 
contained  in  the  lesions  produce  necrobiosis  (under 
the  form  of  caseation  or  softening)  of  the  central  parts 
of  the  latter.  Now,  the  proteins  resulting  from  the 
decomposition  of  the  elements  thus  attacked  excite  a 
local  exudative  inflammation  and  leucocytic  infiltra- 
tion. This  local  reaction  results  in  the  breaking  up 
and  elimination  of  the  tubercular  foci.  The  febrile 
reaction  must  be  attributed  to  the  absorption  of  the 
necrosed  tissues.  (See  page  64,  Gangolphe  and 
Courmont.) 


Microbie  Diseases  Individually  Considered.        237 

The  special  hyperthermic  action  of  tnberciilin  on 
tuberculous  animals  renders  it  a  diagnostic  agent  for 
tuberculosis. 

The  doses  employed  by  different  experimenters 
have  varied  within  very  large  limits;  in  general,  the 
injection  of  20  to  40  centigrams  of  tuberculin  is  suf- 
ficient. JFrom  the  tenth  to  the  twentieth  hour,  oc- 
casionally sooner,  an  elevation  of  temperature  of  from 
one  to  three  decrees  is  observed  in  tuberculous  ani- 
mals.  This  is  therefore  an  excellent  means  of  brine^- 
inff  to  lio-ht  obscure  cases  of  tuberculosis.  Unfor- 
tunately  the  rule  ia  not  without  exceptions:  some 
tuberculous  subjects  do  not  react  at  all  and  a  certain 
number  of  others,  not  tuberculous,  give  the  charac- 
teristic reaction.  In  spite  of  these  exceptions  tuber- 
culin still  furnishes  us  with  a  supplementary  means 
of  diagnosis  and  ought  not  to  be  discarded.  M. 
Nocard  has  shown  that  it  has  no  injurious  action  on 
lactation  or  gestation ;  he  recommends  its  employ- 
ment in  the  sanitary  inspection  of  dairies  where 
milk  is  produced  which  is  intended  for  public  con- 
sumption.* 

On  account  of  its  phlogogenic  and  destructive  ac- 
tion it  might  be  supposed  that  tuberculin  would  act 
as  a  curative  agent,  but,  unfortunately,  this  hypothe- 

*  [Tuberculin  during  the  last  three  years  has  been  very  exten- 
sively tested  in  Europe  and  in  America  and  the  results  obtained 
are  still  entirely  in  harmony  with  the  opinion  here  expressed. 
Animals  in  the  last  stage  of  the  disease  do  not  react;  those  which 
from  any  cause  have  an  abnormal  temperature  at  the  time  of  the 
inoculation  are  also  unsuitable.  When  the  test  is  carefully  made 
the  result  is  almost  always  reliable,  although  the  extent  of  the 
thermal  reaction  gives  no  indication  of  the  extent  of  the  diseased 
process  in  the  animal. — (D.)] 


238  Manual  of  Veterinary  3Ilcrohlotogy. 

sis  lias  not  been  confirmed ;  the  numerous  tests 
which  have  ah'eady  been  made  have  shown  that  tuber- 
culin, instead  of  exerting  a  curative  efiect,  may  be 
positively  harmful  and  cause  the  extension  if  not  the 
generalization  of  the  disease.  The  reagent  is,  in 
reality,  without  effect  on  the  bacillus,  whilst  the  in- 
flammatory reaction  which  develops  around  the 
tubercles  causes  an  aggregation  of  leucocytes  which, 
becoming  charged  with  microbes,  transport  these  to 
points  outside  of  the  original  lesion  where  they  can 
incite  new  centers  of  disease ;  this  inflammatory  re- 
action can,  further,  become  directly  harmful  when 
the  tubercles  are  numerous  and  occupy  a  large  ex- 
tent of  an  important  organ. 

Etiology  and  pathogeny. — Contamination  with  tuber- 
culosis is  most  frequently  indirect,  but  may  also  take 
place  in  a  direct  manner. 

Instances  in  which  physicians  and  veterinarians 
have  contracted  the  disease  in  making  autopsies  of 
diseased  men  or  aiiimals  are  incontestible,  though 
fortunately  rare.  The  virus  inoculated  through  a 
wound,  in  such  cases,  occasions  first  of  all  a  more  or 
less  limited  cutaneous  tuberculosis  which  may  later 
become  generalized. 

Transmission  of  the  disease  from  mother  to  foetus 
constitutes  another  example  of  immediate  contagion. 
This  mode  of  transmission,  although  now  placed  be- 
yond doubt  both  for  animals  and  mankind,  is  actu- 
ally of  rare  occurrence;  the  tubercle  bacillus  is  in 
reality  confined  to  the  specific  lesions  and  only  ex- 
ceptionally circulates  in  the  blood ;  moreover,  it  has 
not  yet  been  demonstrated  that  it  is  capable  of  pass- 
ing  through    the  villosities    of  the   intast    chorion, 


( 


Microbic  Diseases  Indkidiially  Considered.       239 

intra  uterine  propagation  appearing  rather  to  depend 
upon  some  tubercular  alteration  of  the  maternal 
placenta.  Johne  has  noted  the  existence  of  bacillar 
lesions  in  the  liver  and  lung  of  a  foetus  found  in  a 
phthisical  cow.  MM.  Malvoz  and  Brouwier  have 
communicated  two  cases  of  cons^enital  tuberculosis 
in  the  calf;  the  first  of  these  cases  is  quite  convinc- 
ing :  the  fcetug  was  removed  from  the  healthy  womb 
of  a  cow  affected  with  the  generalized  disease;  the 
second  describes  the  case  of  a  calf  six  weeks  old,  the 
origin  of  which  was  not  determined,  but  in  which 
the  lesions  were  regarded  by  the  authors  as  congenital 
because  they  were  located  in  the  same  organs  as  in 
the  first  case,  that  is,  in  the  liver,  and  hepatic  and 
bronchial  lymph  nodes.  From  the  absence  of  intes- 
tinal and  pulmonary  lesions  it  was  inferred  that  the 
infection  could  only  have  taken  place  through  the 
umbilical  vein. 

The  presence  of  the  bacillus  having  been  demon- 
strated in  the  semen,  some  authors  have  been  led  to 
believe  in  the  direct  transmission  from  father  to  off- 
spring by  infection  of  the  ovum.  The  special  locali- 
zation in  the  liver  in  well  observed  cases  of  congenital 
tuberculosis  contradicts  this  manner  of  view. 

The  tubercular  virus  may  be  directly  transmitted 
from  a  diseased  to  a  healthy  individual  through  sex- 
ual intercourse,  either  from  the  female  to  the  male, 
or  inversely. 

Tuberculosis  is  usually  communicated  indirectly. 
The  virulent  matters  rejected  by  the  diseased  (sputa 
of  phthisical  patients,  nasal  discharge  and  excrements 
of  animals)  and  deposited  on  the  ground,  becoming 
dried  and  pulverulent,  are  carried  with  the  air  into 


240  Manual  of  Veterinary  Microbiology . 

the  respiratory  passages  of  healthy  individuals,  or 
are  deposited  on  their  food.  Sputa  or  nasal  discharge 
may  also  be  directly  ingested  by  animals  ;  many  in- 
stances of  the  propagation  of  human  tuberculosis  to  the 
dog  in  this  way  have  been  recorded  and  it  is  probable 
that  in  the  stables  a  considerable  number  of  cattle 
contract  the  disease  by  consuming  forage  directly 
soiled  by  the  expectorations  of  their  ngighbors. 

The  milk  of  phthisical  cows  appears  also  to  be  an 
important  carrier  of  the  germ;  there  is  a  difference 
of  opinion  on  the  question  whether  or  not  the  udder 
can  allow  the  passage  of  bacilli  into  the  milk  without 
itself  becoming  invaded  by  the  tubercular  process; 
some  writers,  basing  themselves  upon  the  result  of 
numerous  tests,  have  come  to  the  conclusion  that  this 
does  occur.  However  that  may  be,  the  difficulty  of 
deciding  as  to  the  non-existence  of  tubercles  in  the 
mammar}^  glands  furnishes  a  sufficient  reason  for  ex- 
cluding from  consumption  all  milk  to  which  such 
suspicion  is  attached.  Such  milk  is  a  dangerous  food 
for  human  beings  and  also  constitutes  a  source  of 
infection  for  animals  to  which  it  is  fed  without  pre- 
vious cooking. 

The  flesh  of  cattle  affected  with  tuberculosis  and 
slauofhtered  for  the  market  also  becomes  virulent  un- 
der  certain  conditions  but  too  little  known.  A  cer- 
tain number  of  inoculations  which  have  been  made 
with  muscle  juice  coming  from  such  animals  have 
given  positive  results,  although  in  the  great  majority 
of  cases  the  results  of  these  inoculations  have  been 
negative.  Nevertheless  the  positive  results  obtained 
are  sufficient  to  establish  the  possible  danger  of  the 
flesh  of  X)htliisical  cattle  and  to  indicate  the  necessity 


Microbic  Diseases  Individually  Considered.      241 

of  compulsory  exclusion  of  such  flesh  from  public 
consumption.  This  question  has  been  lengthily  dis- 
cussed in  the  various  congresses;  without  insisting 
further  on  the  matter  we  will  say  that  it  is  clearly 
connected  with  the  question  of  the  compulsory 
slaughter  of  all  tuberculous  animals.  Indeed,  before 
any  diminution  in  the  amount  of  flesh  liable  to  seizure 
can  be  obtained  the  contagion  must  be  checked  be- 
tween the  living  individuals.  But,  in  the  absence  of 
any  special  provision  of  sanitary  police  in  regard  to 
such  cases,  the  owners  retain  until  the  last  stage,  and 
in  contact  with  healthy  cows,  those  animals  which, 
on  account  of  their  poor  condition,  they  are  unable 
to  sell  but  the  milk  of  which  still  secures  for  them  a 
certain  amount  of  profit. 

"We  have  now  reviewed  the  different  means  by 
which  the  germs  of  tuberculosis  are  transported  from 
diseased  to  healthy  subjects.  The  receptivity  of  the 
subject  Inlays  an  important  role  in  the  genesis  of  the 
process.  It  is  very  often  dependent  upon  a  special 
predisposition  to  the  disease  ;  this  aptitude  to  contract 
tuberculosis  may  be  acquired,  in  which  case  it  results 
from  the  prolonged  influence  of  bad  hygienic  condi- 
tions, or  it  may  be  transmitted  to  an  individual  by  his 
ancestors.  Heredity  of  the  predisposition  is  a  very 
common  occurrence  and  one  especially  well  recog- 
nized in  the  human  family. 

Acute  or  chronic  catarrhal  affections  of  the  respi- 
ratory or  alimentary  passages  favor  the  implantation 
of  the  tubercular  virus  either  by  diminishing  the 
resistance  of  the  tissues  and  of  the  organism  or  by 
producing  solutions  of  continuity  by  which  the  germs 
21 


242  Manual  of  Veterinary  Microbiology. 

may  obtain  entrance.  The  addition  to  pulverulent 
virus  of  bodies  of  an  irregular  shape,  capable  of 
wounding  the  respiratory  mucous  membrane,  exerts 
a  similar  influence.  Joline  has  demonstrated  the 
great  frequency  of  tuberculosis  in  cows  which  respire 
the  fumes  of  iron  foundries;  these  fumes  are  always 
loaded  witb  fine  metallic  particles. 

To  the  number  of  circumstances  favoring  the  pene- 
tration of  the  tubercle  bacillus  into  an  organism  must, 
further,  be  added  the  simultaneous  presence  of  other 
microbes  which  prepare  the  field  for  the  former.  As- 
sociations of  this  kind  may  even  start  into  renewed 
activity  a  tubercular  focus  which  had  long  been  latent 
and  regarded  as  extinct. 

Tlie  typical  tubercular  lesion,  the  tubercle,  is  not 
specific  of  the  disease  ;  it  consists  in  an  inflammatory 
nodule  of  peculiar  structure  which  develops  under 
the  influence  of  multiple  causes  among  which  may 
be  mentioned  microbes  (actinomyces,  zoogloea  of 
Malassez  and  Yignal,  pseudo-tubercle  bacillus  of 
Courmont,  etc.),  animal  and  vegetable  parasites  (do- 
modex  foliculorum,  eggs  of  the  strongylus  vasorum, 
aspergillus,  etc.),  and  non-vital  agents  (powders  of  can- 
tharides,  pepper,  and  lycopod,  and  croton  oil).  The  tu- 
bercle bacillus  must  act  by  a  mechanism  similar  to  the 
preceding  causes,  that  is,  through  the  irritation  which 
it  excites  in  the  elements  wdiich  surround  it.  These 
elements  are  variable  ;  they  may  consist  of  epithelial 
cells,  endothelial  cells,  or  the  fixed  cells  of  the  con- 
nective tissue,  and  along  with  these  should  be  men- 
tioned the  wandering  cells  or  leucocytes  which  are 
every-where  present  and  may  play  an  important  part. 
The  cells  in  contact  with  the  bacillus  increase  in  size, 


Microbic  Diseases  Individually  Considered.       248 

tlieir  nuclei  divide,  and  this  is  quickly  followed  by 
the  division  of  the  cell  body.  Simultaneously,  the 
elements  take  a  polyhedral  form  (epithelioid  cells). 
This  division  continues  and  gives  birth  to  a  mass  of 
new  cells  which  constitutes  the  first  stage  of  the 
tubercle.  In  the  course  of  this  initiatory  period  a 
certain  number  of  elements  may  break  up  and  dis- 
appear, but,  as  a  rule,  those  which  are  directly  in 
contact  with  the  bacillar  focus,  around  the  center  of 
irritation,  acquire  considerabledimensions,  their  nuclei 
continuing  to  multiply  whilst  the  cell  body  remains 
single  (giant  cells) ;  these  giant  cells,  however,  are 
also  formed,  at  least  under  certain  circumstances,  by 
the  fusion  of  several  epithelioid  cells.  When  the 
process  begins  in  the  interior  of  the  blood  vessels  the 
leucocytes  participate  in  it  from  the  first,  but  in  the 
opposite  case  they  only  intervene  at  a  later  stage  by 
emigrating  toward  the  invaded  parts  in  order  to  en- 
ter into  the  struggle  against  the  intruding  germs; 
they  then  conduct  themselves  like  the  elements  men- 
tioned above.  During  this  time  there  is  formed  at 
the  periphery  of  the  epithelioid  zone  a  layer  com- 
posed of  leucocytes  and  fixed  cells  in  way  of  mul- 
tiplication, which  in  some  degree  limits  or  temporarily 
arrests  the  extension  of  the  process. 

The  giant  cells  especially  act  as  phagocytes  ;  they 
contend  against  the  bacilli,  impair  their  vitality  and 
tend  to  bring  about  their  degeneration.  Metschni- 
koii'  has  described  a  series  of  involution  forms  of 
bacilli  in  the  giant  cells  of  the  spermophile.  The 
epithelioid  and  lymphoid  cells  have  the  same  prop- 
erty. Both  giant  cells  and  epithelioid  cells  may  be 
absent   when  the   bacilli   are  extremely   virulent  or 


244  3iauual  of  Veterinary  Mierohiotogy . 

meet  with  an  organism  endowed  with  great  recep- 
tivity; in  such  case  these  protective  elements  have 
not  time  to  become  developed  and  the  tubercle  is  al- 
most entirely  lymphoid. 

The  extension  of  the  inflammatory  pjrocess  to  the 
capillaries  involves  their  obliteration  and  the  absence 
of  the  reparative  plasma  in  the  central  parts  of  the 
tubercle.  Thus  is  explained  the  necrobiosis  (coagu- 
lative  necrosis)  so  frequent  in  this  lesion,  although 
the  influence  of  the  secretions  of  the  bacillus  upon 
the  organic  elements  must  also  be  taken  into  account 
in  this  connection.  This  toxic  action  of  the  bacillus 
is  the  more  pronounced  in  inverse  proportion  to"  the 
resisting  power  of  the  organism  ;  thus,  in  spermo- 
philes  the  giant  cells  of  which  destroy  many  bacilli  and 
establish  their  superiority  over  them,  caseous  masses 
are  not  found  even  after  a  tuberculosis  of  long  dura- 
tion. 

Tubercular  lesions  are  usually  localized  at  the  point 
of  entry  of  the  germs;  the  disease  is,  therefore,  pri- 
marily local,  and  it  may  definitely  remain  in  this  con- 
dition. More  frequently,  however,  it  extends,  and 
this  extension  takes  place  in  diflerent  ways.  In  man 
and  the  large  animals  extension  occurs  chiefly  by  the 
lymphatics,  but  it  may  also  occur  by  way  of  the  blood 
circulation  when  the  bacilli  have  penetrated  into  the 
blood  through  ulceration  of  a  vein  at  a  diseased  fo- 
cus, or,  indeed,  through  the  medium  of  the  lymphatic 
vessels. 

We  have  already  seen  that  the  first  mode  of  propa- 
gation predominates  in  the  guinea  pig,  whilst  it  is 
only  accessory  in  the  rabbit. 

Virulent  products  coming  from  one  part  of  the  or- 


Microbic  Diseases  Individually  Considered,      245 

gauism  may  be  transported  to  another  part  by  the 
movements  of  the  fluids  in  certain  of  the  body  cavi- 
ties; virulent  expectorations  which  are  swallowed  by 
the  diseased  animal  can  thus  infect  the  digestive 
canal. 

The  localization  of  the  lesions  is  dependent  upon 
special  predispositions  of  tissues  or  organs.  This 
fact  has  been  demonstrated  by  the  experiments  of 
Schuller,  who  showed  that  a  contusion  produced  in 
one  of  the  articulations  in  a  subject  artificially  in- 
fected by  any  method  whatsoever  incites  the  evolu- 
tion of  a  tubercular  arthritis. 

Tubercular  lesions  may  become  purulent  in  the 
absence  of  special  pyogenic  germs;  the  Koch  bacil- 
lus, therefore,  secretes  a  pyogenic  substance.  The 
injection  of  a  culture  in  which  the  bacilli  have  been 
killed  by  heat  is  followed  by  an  abscess. 

Cultures  sterilized  and  freed  from  bacilli  are  desti- 
tute of  all  power  of  producing  tubercles  in  healthy 
individuals;  when  injected  to  tuberculous  animals 
they  give  the  reaction  of  Koch's  tuberculin.  The 
tubercular  poison  which  occasions  the  specific  neo- 
plasms is,  therefore,  absent  from  the  soluble  portion 
of  the  cultures;  according  to  Straus  and  Gamaleia 
it  exists  in  the  bacilli  themselves  and  persists  after 
their  death.  Subcutaneous  inoculation  of  dead  ba- 
cilli causes  a  local  abscess.  Intra-peritoneal  inocula- 
tion is  followed  by  a  tubercular  peritonitis  without 
other  lesion.  Venous  injection  results  in  a  pulmo- 
nary tuberculosis  in  which  the  bacilli  occur  with 
their  special  staining  characteristics  unimpaired,  but 
the  tubercles  thus  obtained  are  not  infective  and  have 
no  tendency  to  become  generalized.     When  the  dose 


246  Manual  of  Veterinary  Microbiology. 

inoculated  is  sufficiently  large  they  cause  the  death 
of  the  animal  like  the  tubercles  of  living  bacilli,  and 
with  the  same  general  symptoms.  Inoculation  of  a 
small  dose  of  dead  bacilli  is  followed  by  temporary 
loss  of  condition,  and  the  subject  becomes  much 
more  sensitive  to  a  later  inoculation  with  virulent 
bacilli. 

Tuberculosis  and  scrofula. — The  lesions  of  scrofula 
are  of  a  tubercular  nature;  they  contain  the  Koch 
bacillus. 

M.  Arloing  has  shown  that  the  virus  of  tuberculo- 
sis and  that  of  scrofula  always  infect  the  guinea  pig, 
whilst  the  former  only  is  virulent  for  the  rabbit.  He 
has  also  shown  that  local  tubercular  lesions  are  occa- 
sioned bv  bacilli  which  have  become  more  or  less  at- 
tenuated;  sometimes  these  local  lesions  are  but 
slightly  virulent  and  are  of  a  scrofulous  nature; 
sometimes  they  are  more  active,  resembling  tubercu- 
losis properly  so  called,  and  like  this  have  a  greater 
tendency  to  extension. 

M.  Arloing  is  of  opinion  that  the  bacillus  is  attenu- 
ated in  scrofula;  M.  ISTocard,  on  the  other  hand,  holds 
that  the  diminished  activity  of  the  scrofulous  virus  in 
the  rabbit  is  due  to  the  feeble  receptivity  of  this 
species  for  tuberculosis  and  to  the  poverty  of  this 
virus  in  bacilli. 

The  virulence  of  scrofulous  products  is  augmented 
by  their  passage  through  the  organism  of  the  guinea 
pig;  whilst  tuberculization  is  slow  in  the  first 
guinea  pig  it  becomes  more  and  more  rapid  in  the 
others  inoculated  later  in  the  same  series. 

These  observations  concerning  scrofula  of  man  are 


llicrobic  Diseases  Individually  Considered.      247 

applicable  to  the  scrofulo-tuberculosis  of  the  pig 
(j^ocard). 

MM.  Courmont  and  Dor  have  succeeded  in  produc- 
ing local  articular  tuberculosis  in  the  rabbit  by  intra- 
vascular inoculation  of  attenuated  bacilli;  one  or 
several  articulations  were  attacked,  whilst  the  viscera 
remained  unaffected. 

Tuberculosis  of  mammals  and  avian  tuhercidosis. — 
The  question  as  to  the  identity  of  these  diseases  has 
given  rise  to  much  discussion.  "We  will  describe  first 
of  all  their  differential  characters  : 

The  bacillus  of  avian  tuberculosis  is  longer  than 
that  of  the  disease  in  mammals. 

It  grows  on  the  different  media  when  taken  di- 
rectly from  the  diseased  animal,  that  of  the  mamma- 
lian disease  only,  in  a  satisfactory "^nianner,  after 
several  transfers  upon  serum. 

The  vegetation  of  the  bacilli  of  fowls  is  more  rapid ; 
their  cultures  on  solid  media  are  thick,  moist  and 
luxuriant;  those  of  the  bacillus  of  man  are  meager, 
dry,  scaly  and  of  dull  appearance. 

Cultures  derived  from  fowls  preserve  their  vitality 
longer  (ten  months  at  least)  than  those  coming  from 
man  (six  months). 

The  avian  bacillus  grows  at  a  temperature  as  high 
as  43°;  that  of  man  ceases  to  grow  at  41°. 

Avian  tuberculosis  is  with  difficulty  transmitted  to 
the  guinea  pig  and  the  lesions  do  not  become  gener- 
alized as  in  that  which  is  derived  from  the  human 
being. 

The  rabbit,  although  no  more  sensitive  to  the 
tuberculosis  of  fowls  than  to  that  of  mammals,  shows 
a  much  great  susceptibility  to  the  former  than  the 


248  Manual  of  Veterinary  Microbiology. 

guinea  pig.  According  to  Straus  and  Gamaleia,  avian 
tuberculosis  gives  rise  only  to  Yersin's  septicsemic 
type  of  the  disease  when  it  is  inoculated  in  the  veins 
of  the  rabbit. 

The  dog  readily  contracts  human  tuberculosis;  it 
does  not  take  the  tuberculosis  of  fowls. 

Fowls  are  refractory  to  human  tuberculosis  whilst 
very  sensitive  to  inoculations  of  avian  tuberculosis. 
The  lesions  become  localized  in  the  abdominal  organs, 
occasionally  in  the  lungs,  often  also  in  the  marrow  of 
bones  (causing  lameness). 

The  question  is  whether  or  not  these  differences  are 
sufficiently  important  to  justify  us  in  regarding  the 
two  bacilli  as  distinct  species. 

Both  bacilli  have  the  same  form ;  the  differences  in 
size  which  have  been  observed  are  of  no  importance ; 
long  bacilli  may  be  seen  in  mammals  and  short  bacilli 
in  fowls.  Moreover,  both  are  liable  to  vary  in  their 
cultures  and  according  to  the  animals  to  which  they 
are  inoculated ;  we  have  seen  the  bacilli  of  avian 
tuberculosis  become  exceptionally  short  when  inocu- 
lated to  the  calf. 

Both  bacilli  behave  alike  toward  coloring  matters. 
They  produce  lesions  showing  the  same  structure  and 
the  same  general  evolution. 

The  differential  characters  drawn  from  cultures  are 
not  absolute. 

The  inoculation  of  avian  tuberculosis  to  the  guinea 
pig  occasionally  causes  a  generalization  quite  similar 
to  that  regularly  occasioned  by  human  tuberculosis. 
Out  of  twenty-seven  guinea  pigs  inoculated  with  the 
spontaneous  lesions  of  the  former  disease  five  showed 
a  local  abscess,  seven  a  discrete  visceral  tuberculosis, 


Microhic  Diseases  Indimdualtij  Comsidered.     249 

and  two  the  generalized  disease  (Cadiot,  Gilbert  and 
Roger).  Avian  tuberculosis  which  had  acquired 
greater  virulence  by  passing  through  the  organism 
of  the  rabbit  killed  seven  out  of  eight  guinea  pigs 
which  received  it  in  the  subcutaneous  cellular  tissue 
(Courmont  and  Dor).  In  this  case,  therefore,  the 
bacillus  from  fowls  behaved  exactly  like  that  from 
mammals. 

According  to  an  experiment  of  our  own  the  avian 
bacillus  inoculated  in  the  cellular  tissue  of  the  calf 
causes  a  disease  exactly  like  the  human  bacillus  ;  as 
with  the  latter,  the  evolution  is  slow  and  remains  for 
a  long  time  limited  to  the  glands  receiving  the  lymph 
from  the  place  of  inoculation. 

The  non-receptivity  of  fowls  for  mammalian  tuber- 
culosis is  not  absolute;  out  of  numerous  tests  which 
have  been  made  a  certain  number  have  given  positive 
results  ;  the  lesions,  however,  were  always  less  gener- 
alized than  with  the  avian  tuberculosis. 

Bacilli  derived  from  avian  tuberculosis,  and  which 
had  not  passed  through  fowls  for  at  least  five  years, 
were  found  to  have  become  more  active  for  mammals 
and  produced  a  generalized  tuberculosis  in  rabbits, 
guinea  pigs  and  chickens.  From  the  liver  of  one  of 
those  chickens  four  guinea  pigs  were  inoculated,  none 
of  which  became  tuberculous.  A  si  ngle  passage  through 
the  chicken,  therefore,  was  sutficient  to  impair  the 
virulence  for  mammals  of  these  avian  bacilli  which 
previously  had  acquired  a  virulence  approaching  that 
of  the  human  specimen. 

The  bacillus  of  fowls  becomes  more  active  for  mam  • 
mals  and  less  active  for  fowls  by  passing  through  the 
organism  of  mammals.    This  fact  has  been  proved  by 


250  Manual  of  Veterinary  Microbiology. 

MM.  Cadiot,  Gilbert,  and  Roger  by  means  of  the  gen- 
eralized lesions  which  they  obtained  in  two  guinea 
pigs  with  virus  coming  from  the  pheasant.  After 
three  passages  through  mammals  this  virus  was  inocu- 
lated without  effect  to  two  chickens. 

The  injection  into  animals  of  tuberculin  prepared 
from  the  bacillus  of  fowls  is  followed  by  the  same  ef- 
fects as  the  injection  of  tuberculin  of  human  origin. 

We  must  therefore  regard  the  bacilli  of  avian 
tuberculosis  and  the  bacilli  of  mammalian  tubercu- 
losis as  varieties  of  the  same  species. 

Vaccination. — Tuberculosis  is  essentially  a  recurrent 
disease;  a  first  attack  begets  a  predisposition  to  a 
second.  It  seems,  therefore,  a  priori,  paradoxical  to 
endeavor  to  prevent  it  by  means  of  culture  products. 
Nevertheless,  MM.  Richet  and  Hericourt,  Courmont 
and  Dor,  have  succeeded  in  producing  in  the  rabbit  a 
certain  degree  of  immunity  against  tuberculosis  by  the 
injection  of  sterilized  cultures  of  the  bacillus  of  avian 
tuberculosis;  they  employed  bouillon  cultures  and  ob- 
tained sterilization  by  heat  or  by  filtration.  The  dis- 
ease was  retarded  in  the  majority  of  the  vaccinated 
animals;  in  some  it  was  completely  prevented.  These 
results  justify  us  in  affirming  the  existence  of  vac- 
cinating substances  in  cultures  of  the  tubercle  bacilli 
and  of  indulging  the  hope  that,  some  day,  it  may  be 
possible  to  vaccinate  the  human  being  against  this 
terrible  disease. 

Vaccination  experiments  have  been  made  in  the 
rabbit  by  means  of  the  blood  serum  of  the  dog 
(hsemocyne).  The  investigators  who  have  taken  the 
initiative  in  these  experiments  seem  to  have  obtained 
if  not  absolute  immunity  at  least  a  retardation  of  the 


Mierobic  Diseases  Individually  Considered.      251 

evolution  of  the  experimental  disease.  The  blood  of 
dogs  previously  tuberculized  possesses  properties  more 
active  in  this  respect  than  that  of  healthy  dogs.  These 
results  have  been  utilized  in  therapeutics,  hsemocyne 
having  been  employed  in  the  treatment  of  human 
tuberculosis.  Tests  of  the  same  kind  have  been  made 
with  the  blood  of  the  goat. 

Mierobic  tuberculosis  other  than  that  of  Koch. — "We 
have  already  said  that  microbes  other  than  the  Koch 
bacillus  are  able  to  engender  the  special  inflammatory 
reaction  which  is  characteristic  of  tubercle.  Of  these 
we  are  acquainted  with  several;  we  will  only  refer 
specially  to  the  tubercle-begetting  zoogloea  of  Malas- 
sez  and  Vignal,  and  to  the  bacillus  of  Courmont. 

Zooglceic  tuberculosis  of  Malassez  and  Vignal. — In 
studying  experimental  tubercular  lesions  of  the  guinea 
pig  the  authors  found,  in  place  of  Koch's  bacillus, 
micrococci  associated  in  zoogloea.  These  germs  are 
not  stained  by  Ehrlich's  method;  they  maybe  demon- 
strated by  the  following  process  : 

Sections  are  left  during  two  or  three  days  in  a  mix- 
ture of: 

Two  per  cent  solution  of  carbonate  of 

soda,        ......     10  volumes. 

Saturated  aniline  water,  .         .  5         " 

Absolute  alcohol,         ....       3         " 

Solution  made  with  9  vols,  of  distilled 
water  and  1  vol.  of  concentrated  so- 
lution of  methylene  blue  in  90  per 
cent  alcohol,        ....  3         " 

They  are  washed  with  water,  dehydrated  in  abso- 


252  Manual  of  Veterinary  Microbiology. 

lute  alcohol  colored  with  methylene  blue,  and  cleared 
in  oil  of  bergamot  or  turpentine. 

This  solution  is  a  combination  of  the  two  solutions, 
staining  and  decolorizing,  of  Malassez  and  Vignal's 
original  process  (see  page  110). 

The  bacterial  elements  are  short,  rounded  or  slightly 
elongated,  associated  in  chains  or  in  small  groups,  or 
more  frequently  in  large  groups  or  zoogloea. 

Zoogloeic  tuberculosis  is  transmissible  from  guinea 
pig  to  guinea  pig  by  inoculation  and  gives  rise  to 
generalized  lesions  like  the  tuberculosis  of  Koch; 
but  death  supervenes  at  the  end  of  six  to  ten  days, 
that  is,  much  more  rapidly  than  in  the*  case  of  the 
latter. 

The  authors  were  inclined  to  think  from  their  first 
observations  that  the  zoogloea  and  the  Koch  bacillus 
were  the  same  micro-organism  under  two  different 
forms ;  now,  however,  they  must  be  regarded  as  ab- 
solutely distinct  germs. 

M.  Nocard  had  the  opportunity  of  studying  an  en- 
zootic of  zoogloeic  tuberculosis  in  which  all  the 
chickens  of  a  farm  succumbed  to  the  disease.  The 
tubercles,  in  all  cases,  had  their  seat  in  the  lungs,  a 
situation  in  which  they  are  hardly  ever  seen  in  gen- 
uine tuberculosis.  Moreover,  Koch's  bacillus  was 
absent,  whilst  the  zoogloeae  were  abundantly  repre- 
sented in  the  lesions. 

MM.  ISTocard  and  Masselin  produced  zoogloeic 
tuberculosis  by  inoculating  the  guinea  pig  with  the 
nasal  discharge  coming  from  a  cow  suspected  of 
phthisis,  and  which,  at  the  autopsy,  was  found  to  be 
exempt  from  this  disease.     The  cocci  found  in  the 


Microbic  Diseases  Individually  Considered.       253 

guinea  pig  were  cultivated  and  successfully  inocu- 
lated to  the  guinea  pig  and  the  rabbit. 

Bacillar  tuberculosis  of  Courmont. — M.  Courmont 
found  in  tubercular  lesions  of  the  pleura  in  an  ox — 
lesions  which  did  not  contain  Koch's  bacillus — a  short 
bacillus  with  its  substance  condensed  at  the  two  ex- 
tremities and  with  a  clear  slightly  constricted  median 
zone;  this  bacillus  is  never  associated  in  chains  or 
in  diplo-bacilli;  it  is  aerobic  and  anaerobic.  It  is 
easily  cultivated  and  grows  rapidly  in  all  the  culture 
media  and  at  wide  limits  of  temperature,  even  up 
to  46°. 

Guinea  pigs  succumb  in  four  to  eight  days  with  a 
local  oedema  and  great  enlargement  of  the  spleen,  but 
without  tubercular  lesions.  The  bacilli  are  abundant 
in  the  serosity  of  the  oedema  and  in  the  blood;  after 
several  passages  through  the  guinea  pig  a  caseous 
abscess  develops  at  the  place  of  inoculation. 

Rabbits  contract  a  more  or  less  complete  tuber- 
culosis; an  abscess  forms  at  the  place  of  inoculation, 
and,  after  death,  disseminated  or  confluent  tubercles 
are  found  in  the  spleen,  liver,  and  lungs.  These 
tubercles  have  the  classic  structure ;  they  do  not  con- 
tain Koch's. bacillus  but  those  described  above. 

A  culture  twenty  days  old  having  been  inoculated 
to  guinea  pigs  the  latter  died  in  less  than  ten  days 
with  a  generalized  tuberculosis  in  which  the  lesions 
contained  Courmont's  bacillus.  The  property  of  be- 
getting tubercles  in  the  guinea  pig  appears  to  exist 
in  cultures  only  from  the  twentieth  to  the  twenty- 
fifth  day;  at  other  times  the  inoculated  guinea  pig 
dies  without  tubercles.  The  tubercles  of  the  guinea 
pig  kill  the  rabbit,  but  without  tubercular  lesions. 


254  Manual  of  Veterinary  31icrohiology. 

Courmont's  bacillus,  therefore,  produces  a  tubercu- 
losis in  the  ox;  the  lesions  of  the  ox  have  direct 
tubercle  begetting  action  on  the  rabbit  but  not  on  the 
guinea  pig,  except  under  the  special  conditions  men- 
tioned above.  We  know,  however,  that  the  guinea 
pig  is  more  sensitive  to  mammalian  tuberculosis  than 
the  rabbit,  hence,  besides  the  character  of  the  bacil- 
lus, there  is  a  manifest  diiFerence  between  the  two 
diseases.  Furthermore,  the  experimental  tubercu- 
losis obtained  in  the  guinea  pig  by  the  subcutaneous 
inoculation  of  Koch's  bacillus  develops  so  slowly 
that,  on  an  average,  the  lung  is  invaded  only  at  the 
end  of  two  months;  with  the  bacillus  of  Courmont, 
as  also  with  the  zoogloese  of  Malassez  and  Vignal, 
the  guinea  pig  becomes  tuberculized  in  less  than  ten 
days.  Generally,  in  the  rabbit,  the  duration  of  Cour- 
mont's tuberculosis  is  almost  the  same  as  that  of 
Koch's  tuberculosis.  Another  character  important  to 
notice  is  the  presence  of  Courmont's  bacillus  in  the 
blood  of  subjects  tuberculized  by  means  of  this  bacil- 
lus. Finally,  the  disease  generalizes  without  infecting 
the  lymphatic  glands. 

Glanders. 

■  Glanders  is  an  infectious  and  contagious  disease, 
with  progressive  course,  characterized  by  circum- 
scribed and  multiple  alterations  localized  in  the  re- 
spiratory mucosa  (glanders),  or  in  the  skin  (farcy). 
These  two  localizations  may  coexist,  in  which  case 
we  have  to  do  with  the  disease  glanders-farcy.  The 
disease  is  peculiar  to  solipeds  :  horse,  ass,  and  mule; 
it  may  also  develop  in  man  as  a  result  of  accidental 
inoculation  with  virulent  products  coming  from  one 


(OP  THB 
Q"NTT-7T-R=^TT 


Microbic  Diseases  LuUvidually  Considered.      255 

of  these  animals ;  transmission  to  the  lion,  dog,  and 
goat  has  also  been  observed  as  a  result  of  spontane- 
ous contamination. 

The  disease  is  acute  or  chronic  ;  it  is  always  acute 
in  the  ass  and  mule,  as  well  as  in  the  lion.* 

Microbe. — The  bacillus  mallei  is  a  slender,  motile 
rod,  straight  or  slightly  curved,  and  with  rounded 
ends.     It  measures  2/i  to  5/z  in  pj^  ^^ 

length  by  0-5/i  to  1-5/^  in  thick-  V^**^  /v- 

ness,  hence  it  is  thicker  than  the  ^    -k    >r> 

Koch  bacillus,  but  of  the  same  ^^  >$n  ^ 

length.     When  stained  it  shows       y  ^  yigx 

alternating    clear     and    colored        ^    ^  uJSk^" 
spaces  which  give  it  a  granular         '        /xc^ 

,  IT         j-i-    i.      J?  j-i       +.,  Bacillus  mallei.    X 

aspect  recalling  that  of  the  tu-     ^^^^^    From  a  photo- 

bercle  bacillus.  Rosenthal  re-  micrograph.  (Frankel 
gards  these  clear  spaces  as  spores ;  and  Pfeifer.)  —  From 
others,  however,  basing  them-  Sternberg's  Bacteriol- 
selves  on  the  shght  resistance  of  °^^' 
the  bacillus  to  heat,  refuse  to  admit  the  existence  of 
spores. (1) 

The  glanders  bacillus  is  aerobic;  it  occurs  in  the 
pathological  secretions — nasal  discharge,  pus  of  ul- 
cers ;  and  in  the  specific  lesions — farcy  buds,  tuber- 
cles, glanderous  ulcers,  and  inflammation  of  the  cor- 
responding lymphatic  vessels  and  glands,  etc.     It  is 

(1)  Babes  has  shown  that  such  granules  are  present  in  the  ma- 
jority of  bacilli,  even  the  least  resistant,  and  that  they  do  not 
possess  the  resisting  power  of  true  spores.  He  believes  that  they 
exercise  the  same  function  in  the  multiplication  of  bacilli  as  the 
chromatic  part  of  cell-nuclei  in  the  division  of  cells. 

*  [The  sub-acute  or  chronic  form  of  the  disease  seems  to  be  not 
uncommon  in  mules  in  the  Southern  States. — T).] 


256  Manual  of  Veterinary  Microbiology. 

present  in  the  blood  only  in  acute  forms,  and  then  in 
very  small  numbers. 

Action  of  'physical  and  chemical  agents. — The  con- 
tagion of  glanders  is  destroyed  by  two  minutes  ex- 
posure to  a  temperature  of  100°,  but  its  destruction 
can  be  obtained  at  lower  temperature,  provided  the 
action  of  the  heat  is  more  prolonged,  for  example, 
five  minutes  at  65°,  ten  minutes  at  55°.  Glanderous 
pus,  spread  in  a  thin  layer  and  left  to  desiccate  in 
contact  with  the  air,  loses  its  activity  between  the 
second  and  third  days;  hot  and  dry  weather  fa- 
vors its  destruction,  while  cold  and  wet  weather 
retards  it.  Under  the  same  conditions  of  desic- 
cation, but  excluded  from  the  air,  it  yet  shows 
itself  active  after  twenty-six  days.  Virus  rapidly 
and  thoroughly  dried  retains  its  vitality  in  contact 
with  the  air  longer  than  that  which  is  slowly  and  im- 
perfectly dried.  The  discharge  from  the  nose  in  gland- 
ers, when  immersed  in  water,  has  been  found  to  re- 
tain its  virulence  for  eighteen  days.  Virulence  is  not 
readily  destroyed  by  putrefaction;  inoculations  made 
with  the  central  part  of  pieces  of  glanderous  lungs 
abandoned  to  the  air  for  fifteen,  eighteen,  and  even 
twenty-six  days,  have  given  positive  results.  (Cadeac 
and  Malet.) 

The  following  substances  destroy  the  virus  of 
glanders  after  one  hour  of  contact :  carbolic  acid,  2 
per  cent;  sulphuric  acid,  2  per  cent ;  chloride  of  zinc, 
2  per  cent;  saturated  lime  water;  hypochlorite  of 
lime,  1  per  cent;  corrosive  sublimate,  1  to  1,000, 
and  1  to  10,000 ;  sulfate  of  copper,  5  per  cent ;  per- 
manganate of  potash,  5  per  cent;  nitrate  of  silver,  1 


Microbic  Diseases  Individually  Considered.      257 

to  1,000;  chlorine  gas,  aud  sulphurous  acid  gas,  in 
concentrated  solution. 

Cultures. — Cultures  are  easily  obtained  on  the  dif- 
ferent media;  they  require  free  access  of  atmos- 
pheric oxygen  ;  37°  is  the  most  favorable  tempera- 
ture; below  20°  their  growth  is  arrested  except  upon 
glycerin-agar ;  it  also  ceases  at  43°,  and  the  germs 
are  killed  at  55°. 

Bouillons  become  turbid  within  twenty  four  hours 
without  presenting  special  characters. 

On  agar  and  on  serum  it  shows  a  bluish-white 
translucid  growth  in  the  form  of  droplets,  or  in  a 
continuous  layer  which  becomes  opaque  as  it  increases 
in  thickness. 

Potato  is  admirably  adapted  to  the  culture  of  the  ba- 
cillus of  glanders.  On  this  medium  it  forms  a  thick, 
moist,  glistening,  viscid  coating,  which  after  a  few  days 
assumes  a  fawn  color,  gradually  deepening  to  a  bright 
chocolate.  (!N'ocard.)  This  culture  is  characteristic 
and  should  assist  us  in  the  diagnosis  of  doubtful 
cases ;  it  suffices  to  sow  a  particle  of  the  suspected 
product,  previously  diluted,  upon  potato  ;  the  latter 
soon  becomes  covered  with  diverse  growths  among 
which  we  should  recognize  by  their  peculiar  color 
those  due  to  the  glanders  bacillus.* 

Research  and  coloration. — The  bacillus  mallei  shows 
little  affinity  for  the  aniline  colors;  it  does  not 
support  the  Gram  or  Weigert  stains.     The  methods 

*  [Such  simple  culture  tests  can  be  of  value  when  the  suspected 
material  is  obtained  from  a  yet  unopened  skin  nodule  or  from  an 
extirpated  submaxillary  lymph   node,  but  will  rarely  assist  us  in 
the  examination  of  nasal  discharge. — D.] 
00 


258  31anual  of  Veterinary  Microbiology. 

of  double  staining  are  therefore  inapplicable.  Gen- 
erally we  have  recourse  to  Loffler's  blue,  decolorizing 
with  carbolated  water,  at  1  to  300. 

Kiihne  also  recommends  the  following  method  of 
staining:  Sections,  w^ell  freed  from  alcohol,  or  cover 
glasses,  are  placed  in  a  solution  composed  of:  water, 
100;  carbolic  acid,  5;  alcohol,  10;  methylene  blue, 
1-5.  They  are  decolorized  by  a  rapid  passage 
through  water  acidulated  with  hydrochloric  acid,  and 
washed  in  distilled  water.  The  sections  are  dehy- 
drated by  a  short  immersion  in  alcohol,  then  placed 
in  aniline  oil  to  which  has  been  added  a  few  drops  of 
oil  of  turpentine,  then  in  pure  turpentine,  and, 
finally,  in  xylol. 

The  bacillus  of  glanders  is  difficult  to  demonstrate 
in  old  lesions,  where  it  appears  to  break  up  into 
granules  (perhaps  into  spores);  it  is  always  much 
more  abundant  in  acute  lesions. 

Experimental  inoculations. — Solijoeds,  the  sheep,  goat, 
pig,  dog,  cat,  rabbit,  guinea  pig,  field  mouse  and  pig- 
eon take  the  disease  by  inoculation.  The  ox,  white 
mouse,  rat  and  chicken  are  refractory.  The  ass 
always  contracts  acute  glanders  by  inoculation. 
When  the  virus  is  inserted  by  scarifications  in  the 
forehead,  for  example,  an  extensive  ulcer,  with  indu- 
rated and  inflamed  borders,  develops  on  this  region. 
Along  with  this  the  manifestations  of  the  general 
disease  appear  about  the  third  day,  and  the  subject 
quickly  dies.  The  autopsy  reveals  an  eruption  of 
small  reddish  nodules  on  the  respiratory  mucous 
membrane,  pysemic  infarcts  in  the  lungs,  liver,  kid- 
neys, spleen,  marrow  of  bones,  etc. 

In  the  dog  the  insertion  of  the  virus  in  the  skin  or 


31ierobic  Diseases  Indwidaally  Considered.      259 

the  subcutaneous  cellular  tissue  is  sometimes  followed 
by  a  violent  access  of  fever  in  the  course  of  the  third 
day  ;  then  the  local  lesions  appear  in  the  form  of  an 
extensive  engorgement  wliich  bursts  and  ulcerates, 
the  chancre  thus  produced  having  a  great  tendency 
to  spread.  Farcy  buds  and  cords,  and  rodent  ulcers 
often  appear  on  other  parts  of  the  body;  sometimes 
an  intense  and  painful  lameness — expression  of  glan- 
derous arthritis — supervenes  without  apparent  cause, 
the  stifle  being  the  most  frequent  seat  of  the  specific 
inflammations.  Out  of  twelve  dogs  inoculated  by 
Prof.  Reul,  four  died,  three  were  killed,  and  five 
spontaneously  recovered.  Inoculation  of  glanders  to 
the  dog  often  gives,  as  sole  reaction,  a  superficial 
ulceration  wdiich  cicatrizes  in  eight  to  fifteen  days. 

In  the  guinea  pig  inoculation  by  scarifications 
(these  are  made  on  the  neck  or  back)  is  followed  by 
ulceration  of  the  w^)unds  on  the  fifth  to  the  tenth 
da}^;  these  ulcers  may,  later,  cicatrize.  Subcuta- 
neous inoculation  gives  voluminous  abscesses  in  the 
whole  chain  of  lymphatic  glands  proximal  to  the 
place  of  inoculation.  In  both  cases  the  animal  be- 
comes emaciated  and  dies  more  or  less  rapidly  with 
tubercular  foci  in  the  spleen,  liver,  lung  and  lymphatic 
glands.  The  local  lesion — the  ulcer — suffices  to  es- 
tablish the  glanderous  nature  of  the  inoculated  prod- 
ucts. When  the  inoculation  is  made  in  the  perito- 
neum a  pronounced  swelling  of  the  scrotum  is  ob- 
served from  the  second  to  the  third  day,  this  swelling 
indicating  the  specific  inflammation  of  the  testicular 
membranes.  This  peculiarity  can  be  utilized  for  the 
purpose  of  making  a  rapid  diagnosis  of  the  disease 
(Straus). 


260  Manual  of  Veterinary  Microbiology. 

When  glanders  is  inoculated  to  tlie  dog  or  guinea 
pig  by  scarifications  it  may  be  followed  by  a  negative 
result.  Hence,  an  absolute  value  should  be  assigned 
only  to  positive  results,  and  the  suspected  material 
which  has  been  unsuccessfully  inoculated  submitted 
to  further  tests. 

Diagnosis  of  doubtful  cases. — Besides  experimental 
inoculations  to  susceptible  animals,  guinea  pigs,  dog, 
and  ass,  and  the  cultures  on  potato  of  the  suspected 
discharge,  some  have  counseled  the  employment  of 
auto-inoculation.  This  operation  consists  in  inocu- 
lating a  horse  with  the  products,  supposed  to  be  viru- 
lent, coming  from  the  same  animal ;  these  insertions  are 
made  in  the  skin  by  puncture  or  superficial  incision  and 
the  existence  of  glanders  confirmed  if  the  operation  is 
followed  by  the  formation  of  a  chancre;  but,  as  we 
shall  see  later,  no  conclusion  can  be  reached  founded 
on  the  absence  of  the  ulcerous  reaction.  In  default 
of  any  discharge  some  have  resorted  to  extraction  of 
a  swollen  lymph  node  and  examination  of  the  same 
for  the  specific  bacilli.  Finally,  we  may  have  re- 
course to  test  inoculations  with  mallein. 

Mallein. — By  this  name  is  designated  a  glycerin 
extract  of  pure  cultures  of  the  bacillus  of  glanders. 
This  is  the  glanders  lymph,  the  analogue  of  the 
tuberculosis  lymph  or  tuberculin.  The  extract  is 
sterilized  by  heat,  and  diluted  to  ten  times  its  weight 
with  two  per  cent  carbolic  solution. 

The  injection  of  SO  to  50  centigrams  of  this 
dilution  to  glanderous  horses  produces  a  reaction 
characterized  especially  by  dejection,  acceleration  of 
the  pulse,  and  elevation  of  temperature  ranging  from 
1*5°  to  2°,  by  a  hot  cedematous  swelling  as  large  as 


Microhic  Diseases  Individually  Considered.       261 

the  hand  at  the  place  of  inoculation,  and  by  an  ap- 
preciable swelling  of  the  subglossal  lymphatic  glands. 
In  a  healthy  animal  the  same  injection  would  produce 
no  effect.  Mallein  should,  therefore,  facilitate  the 
diagnosis  of  the  disease  in  doubtful  cases. 

Etiology  and  'pathogeny. — The  efficient  cause  of 
glanders  is  the  bacillus  maUei.  This  microbe,  under 
natural  conditions,  multiplies  only  in  the  organism 
of  solipeds  and  its  origin  must  be  looked  for  in 
these  animals.  The  virulent  substances  cast  off  by  a 
glanderous  subject  are  :  nasal  discharge,  pus  of  ulcers, 
saliva,  urine,  pus  of  setons,  and  semen  ;  the  virulence 
of  the  last  four  products,  though  less  constant  than 
that  of  the  first,  is  nevertheless  incontestable  and  has 
been  demonstrated  by  experiment.  To  this  list  must 
be  added,  in  the  case  of  the  cadaver,  the  various 
specific  lesions  and  the  muscles.  Inoculation  of 
guinea  pigs  with  muscle  juice  has  produced  the  dis- 
ease in  a  certain  number  of  cases. 

Contagion  takes  place  by  direct  or  indirect  con- 
tact. There  is  direct  contact  from  the  horse  to  man 
when  the  latter  inoculates  himself  in  manipulating 
or  in  dressing  glanderous  lesions;  from  horse  to 
horse  when  two  horses,  one  of  which  is  glandered, 
occupy  adjacent  stalls  in  a  stable,  or  work  side  by 
side  so  that  they  can  easily  touch  each  other.  The 
disease  is  occasionally  transmitted  through  sexual  in- 
tercourse ;  Zundel  mentions  the  case  of  a  glandered 
stallion  which  infected  more  than  fifty  mares.  The 
eventual  passage  of  the  glanders  bacillus  into  the 
semen  accounts  for  this  mode  of  infection,  whilst 
their  filtration  through  the  placenta  occasions  trans- 
mission   of  the    disease  from    mother   to  foetus,    an 


262  Manual  of  Veterinary  Microbiology. 

occurrence  which  has  been  observed  by  MM.  Cadeac 
and  Malet.  Inter-sexual  and  intra-uterine  contami- 
nation are,  however,  actually  of  rare  occurrence. 

Indirect  contagion  is  much  the  most  frequent.  The 
glanders  virus,  distributed  externally,  contaminates 
the  food,  drinkins:  water  and  litter,  harness,  groom- 
ing utensils,  sponges,  brushes,  curry-combs,  etc.,  the 
walls  of  houses,  mangers,  racks,  and  such  like;  if 
it  meets  with  the  conditions  necessary  for  desicca- 
tion it  will  be  carried  with  the  dust  into  the  sur- 
rounding atmosphere.  The  morbific  germ  is  trans- 
ported on  to  the  healthy  organism  through  the  in- 
termediation of  numerous  vehicles.  Infection  mav 
take  place  through  the  respiratory  passages,  the  ani- 
mal inspiring  air  charged  with  virulent  particles,  bnt 
this  mode  of  contagion  should  be  rarely  effective  in 
glanders  since  desiccation  is  a  puissant  cause  of  the' 
destruction  of  the  bacillns.  The  disease  is  more  cer- 
tainly communicated  by  the  digestive. canal,  through 
swallowing  infected  food  or  water.  This  contamina- 
tion of  the  ingesta  may  result  from  their  immediate 
contact  with  the  products  coming  from  a  diseased 
animal  or  it  may  occur  during  their  storage  in  in- 
fected places. 

In  this  connection  should  be  mentioned  the  danger 
arising  from  the  consumption  of  animals  which  have 
died  or  been  killed  while  suffering  from  the  disease. 
This  danger  exists  not  only  for  the  specific  lesions, 
in  which  the  virulence  is  evident,  but  also  for  the 
flesh.  The  investigations  of  MM.  Cadeac  and  Malet 
have  shown  that  the  juice  of  such  flesh  is  capable  of 
communicating  glanders. 

Finally,  the  virus  may  penetrate  through  the  skin 


Microbic  Diseases  Individaally  Considered.      263 

to  which  it  has  been  carried  in  various  ways  and  es- 
pecially by  the  harness,  grooming  utensils,  litter,  etc.; 
it  gains  entrance  through  accidental  abrasions  of  the 
integument.  According  to  Babes,  however,  the 
glanders  virus  can  make  its  way  into  the  organism 
through  the  intact  skin,  penetrating  the  oriUces  of 
the  hair  follicles.  This  penetration  will  by  facilitated 
by  frictions.  M.  Nocard  undertook  to  test  this  asser- 
tion by  rubbing  an  ointment  charged  with  glanders 
bacilli  on  the  skin  of  three  asses  and  fifteen  guinea 
pigs.  Of  these,  only  two  guinea  pigs  became  glaud- 
ered,  a  result  which  considerably  reduces  the  risk 
which  might  be  inferred  from  the  above  conclusions. 

Certain  circumstances  are  of  such  a  nature  as  to 
favor  the  implantatio-n  of  the  bacilli  of  glanders. 
We  recognize  the  predisposing  influence  of  bad  hy- 
gienic conditions,  excessive  fatigue,  and  chronic  ex- 
hausting diseases.  Chronic  forms  of  glanders  may 
assume  acute  characters  under  the  same  influences. 

The  bacilli  of  glanders  having  once  obtained  en- 
trance into  the  economy  multiply  generally  at  the  place 
of  their  penetration,  thus  producing  local  lesions. 
They  quickly  invade  the  lypmphatic  system  (which 
becomes  the  seat  of  specific  inflammations,  glander- 
ous lymphangitis  and  adenitis)  and  the  blood  ;  by  the 
latter  they  are  carried  throughout  the  system  but 
they  only  develop  in  the  tissues  predisposed  to  their 
attack:  respiratory  mucous  membrane,  integument, 
testicles,  and  synovial  membrane  of  articulations  and 
tendons,  etc. 

The  specific  lesions  present  certain  analogies  with 
those  of  tuberculosis.  The  primary  lesion — the  glan- 
ders tubercle^is  purulent  at  its  center  and  destitute 


2()4  Manual  of  Veterinary  Microbiology. 

of  giant  cells;  besides  this  marked  tendency  to  sup- 
puration, should  be  mentioned  the  early  retrogressions 
which  lead  to  the  ulcerations  characteristic  of  the  dis- 
ease. 

Vaccinations. — Glanders  leaves  behind  it  no  immu- 
nity against  another  attack.  Thus,  auto-inoculations 
and  re-inoculations  performed  upon  animals  already 
affected  with  the  disease  are  followed  by  positive  re- 
sults. In  the  glanderous  guinea  pig  these  inoculations 
determine  local  symptoms  as  intense  and  a  generali- 
zation as  complete  as  at  the  time  of  a  first  insertion; 
in  the  dog  the  second  attack  is  also  generalized  and 
often  as  severe  as  the  first.  According  to  Galtier  the 
dog  can  contract  the  disease  as  often  as  five  times, 
but  the  local  symptoms  become  less  and  less  marked 
In  the  horse  re-inoculations  and  auto-inoculations 
may  prove  abortive  or  may  produce  a  chancre  with 
or  without  lesions  of  the  lymphatics,  but  fever  and  ag- 
gravation of  symptoms  are  never  observed,  the  virus 
seeming  to  limit  its  effects  to  the  point  of  inocula- 
tion. In  the  ass  secondary  inoculations  are  followed 
by  much  more  intense  reactions;  each  insertion  pro- 
duces a  marked  tumefaction  and  a  corresponding 
ulcer,  corded  lymphatics,  glandular  engorgements — 
in  brief — the  effects  of  a  first  inoculation.  (Cadeac 
and  Malet.) 

The  natural  disease,  therefore,  does  not  confer  im- 
munity. Several  attempts  at  artificial  vaccination 
have  been  made.  Strans  obtained  immunity  in  a  dog 
by  the  intravenous  injection  of  a  small  quantity  of 
virulent  culture.  A  bei>ign  disease  is  produced  which 
immunises  the  dog  against  intravenous  inoculation  of 
large  doses. 


Microbic  Diseases  Individually  Considered.       265 

Epizootic  lymphangitis,  or  African  farcy. 

Rivolta  has  described,  and  M.  !N'ocard  confirmed, 
the  presence  in  the  pus  and  lesions  of  African  farcy 
of  "  a  sort  of  micrococcus,  sliglitly  ovoid  and  some- 
what pointed  at  one  of  its  extremities,  measuring  S/i 
to  4//  in  diameter;  its  contour  is  clearly  defined  by  a 
very  refringent  line."  This  organism  (cryptococcus 
of  Rivolta)  is  colored  by  the  Gram-Weigert-Kiihne 
methods ;  but  its  dimensions  and  its  refringence  are 
such  that  it  is  impossible,  according  to  M.  Nocard,  to 
confound  it,  even  when  unstained,  with  any  other 
element. 

Several  practitioners  have  described  the  appearance 
of  chancres  of  acute  glanders  on  the  nasal  mucosa  of 
animals  attacked  by  epizootic  lymphangitis.  The 
demonstration  of  the  cryptococcus  in  these  lesions 
enabled  M.  IsTocard  to  afiirm  that  they  were  related  to 
lymphangitis  and  not  to  glanders.  Moreover,  the 
bacillus  of  this  last  disease  was  lacking. 

Strangles  * 
We  are  indebted  to  Schiitz  for  the  investigation  of 
the  microbe  of  strangles.  It  is  a  streptococcus  which 
occurs  in  short  chains,  in  diplo-  and  in  monococci  in 
the  nasal  discharge  and  in  the  pus  of  the  lymph- 
glandular  inflammations  and  abscesses  symptomatic 
of  the  disease ;  in  long,  tortuous  chaplets  in  sections 
of  the  inflamed  organs.  It  readily  takes  the  differ- 
ent aniline  stains.   Inoculated  under  the  skin  of  the 

*  [Also    called,    in    America,    "  Distemper "    of    horses ;    Fr.. 
Gourme  ;  Ger.  Druse. — D.] 

23 


266  Manual  of  Veterinary  Microbiology. 


horse  it  causes  the  formation  of  an  ahscess.  In  tlie 
mouse*  it  produces,  in  addition,  metp.stases  hy  "v^ay 
of  the  lymphatics  and  blood  vessels.  Natural  in- 
fection takes  place  through  diflerent  channels  but 
more  especially  through  the  respiratory  and  digestive 

mucous     mem- 
^^'     ■  branes.     Its  ab- 

sorption is  facili- 
tated by  the 
presence  of  solu- 
tions of  continu- 
ity, but  it  has 
not  been  shown 
that  these  are 
necessary.  Ac- 
cidental or  ope- 
..  rative  wounds 
also  sometimes 
furnish  ports  of 
Streptococcus  equi,  pus  of  strangles  of  horse,  entry     for      the 


y'*^'A 


•.....•••••••. 


"^.....••* 


X  1000.    (Kitt.) 


Virus;  castration 


wounds,  for  example,  may  be  infected  by  the  surgeon 
himself,  his  hands  or  instruments  being  soiled  with 
the  germs  from  previously  handling  horses  suffering 
from  strangles.  The  disease  is  transmitted  from  the 
mother  to  the  foetus.     Whatever  may  be  its  mode  of 

*  [An  important  differential  test  in  distinguishing  this  disease 
{in  its  less  characteristic  forms)  from  glanders  consists  in  the  in- 
oculation of  mice.  White  and  gray  house  mice  are  highly  sus- 
ceptible and  die  from  inoculation  with  strangles,  but  are  insus- 
ceptible to  glanders.  Field  mice,  on  the  contrary,  die  from  inocu- 
lation with  glanders,  but  develop  only  a  local  lesion  from  inocula- 
tion with  strangles. — Th.  Kitt :  Bacterienkunde,  p.  254.— D.] 


Microbic  Diseases  Indimdually  Considered.      267 

entry  the  germ  appears  to  pass  at  once  into  the  blood 
as  is  indicated  by  the  high  fever  at  the  beginning  of 
the  disease;  it  then  becomes  localized  in  the  lym- 
phatic system.  The  microbic  theory  of  strangles  ac- 
counts for  its  contagiousness,  the  secondary  abscesses 
met  with  in  the  course  of  the  disease,  and  the  sep- 
tico-pysemic  complications  which,  in  certain  cases, 
terminate  it. 

Contagious  acne  of  the  horse. 

This  disease  is  characterized  by  a  pustulous  der- 
matitis which  is  very  readily  transmitted  to  other 
animals.  It  is  generally  benign  but  may  be  more 
severe  and  lead  to  the  production  of  ulcerations  and 
inflammations  of  the  lymphatic  vessels  and  gUinds. 
It  is,  however,  always  easily  distinguished  from  farcy 
by  the  great  tendency  to  cicatrization  of  the  ulcers 
which  it  occasions ;  in  farcy,  moreover,  true  pustules 
do  not  occur.  Acne  is  distinguished  from  horse-pox 
or  variola  of  the  horse  by  the  fact  that  the  eruption 
in  this  last  disease  is  always  localized  in  the  lips, 
nostrils,  and  pasterns. 

Dieckerhofi'  and  Grawitz  discovered  in  the  pus  of 
acne  a  short  bacillus  (2/i)  which  they  cultivated  and 
the  culture  of  which,  rubbed  into  the  skin  of  the 
horse,  reproduced  the  disease.  The  guinea  pig  suc- 
cumbs in  twenty-four  hours  when  subjected  to  the 
same  treatment.  These  cultures  are  also  pathogenic 
for  the  ox,  sheep,  dog,  and  rabbit.  Inoculated  under 
the  skin  of  the  mouse  it  gives  rise  to  the  formation  of 
an  abscess. 

The  natural  disease  is  transmitted  by  means  of  the 
grooming  utensils,  harness,  blankets,  etc.;  thus,  it  is 


268  Manual  of  Ycterinary  Microbiology. 

not  uncommon  to  see  it  localized  on  the  regions  cov- 
ered by  the  saddle  or  girth. 

Actinomycosis. 

Actinomycosis  is  a  disease,  most  frequently  of  a 
local  character,  caused  by  a  vegetable  parasite,  the 
actinomyces.  The  lesions  by  which  it  is  character- 
ized have  long  been  recognized  in  practice,  but  their 
true  nature  was  entirely  unknown  before  the  inves- 
tigations of  Bollinger,  the  different  names,  such  as 
osteosarcoma,  osteoporosis,  spina-ventosa,  cancer  or  farcy 
of  the  bones,  etc.,  by  which  the  maxillary  tumors  of 
cattle  were  designated  reflecting  the  A^ery  diverse  and 
somewhat  vague  opinions  of  the  various  writers  upon 
these  productions. 

The  discovery  of  a  special  fungus  in  the  majority 
of  these  tumors  has  enabled  us  to  classify  them  with 
the  parasitic  infections  and  explain  their  great  in- 
tractability. 

The  facts  established  by  the  authors  in  their  first 
communication  on  actinomycosis  have  been  repeat- 
edly confirmed  since  then  in  both  human  and  vet- 
erinary medicine,  and,  referring  here  to  the  latter 
branch  of  medicine  only,  the  lesions  of  this  disease 
have  been  found  in  other  parts  of  the  body  than  in 
the  maxillse.  They  have  been  met  with  in  the 
tongue,  pharynx,  reticulum,  liver,  nasal  cavities, 
larynx,  lungs,  neck,  and  vertebrse. 

In  the  pig  they  have  been  observed  in  the  muscles, 
lungs,  amygdalae  and  mammae;  in  the  horse  in  cer- 
tain cases  of  scirrhous  cord.  A  case  has  also  been  re- 
corded in  the  dog. 

Characters  of  the  parasite. — The  actinomyces  (ray 


Microbic  Diseases  Individually  Considered.       269 

fungus)  occurs  in  the  specific  tumors  in  the  form  of 
yellow  or  occasionally  colorless  grains;  when  the  ma- 
terial in  which  they  are  contained  is  spread  out  on  a 
glass  slip  the-smallest  of  these  grains  appears  some- 
what like  grains  of  sand;  the  larger  are  formed  hy 
the  union  of  primary  granules  and  are  of  various 
forms.  These  grains  are  most  frequently  cretaceous, 
having  a  hard,  stony  consistence.  In  size  they  vary 
from  0-1  millimeter  to  1  millimeter,  or  more. 

They  are  composed  of  one  or  several  colonies  of  a 
fungus  the  elements  of  which  are  arranged  in  rays. 
In  each  colony  there  may  be  distinguished  : 

1st.  A  central  zone,  formed  of  very  fine  filaments 
ramifying  and  intermingled  in  a  close  felted  net-work. 
The  diameter  of  these  filaments  is  uniform  in  all  parts 
of  the  central  zone;  in  structure  they  consist  of  hol- 
low cylinders,  each,  at  intervals,  containing  a  nucleus 
which  readily  takes  up  coloring  matters. (1) 

The  size  of  this  central  part  of  the  actinomyces 
corresponds  with  that  of  the  tuft  or  colony;  small  in 
microscopic  grains  it  is  of  much  larger  dimensions 
in  those  tufts  which  have  acquired  a  considerable 
volume. 

2d.  A  peripheral  zone,  rendered  conspicuous  by  the 
radiating  elements  of  which  it  is  composed ;  these 
elements  are  pyriform  with  their  large  extremities 
losins:  themselves  in  the  tissue  which  surrounds  the 
colony  and  even  occasionally  penetrating  into  the 
adjacent  cells,  and  their  slender  ends  passing  into  the 

(1)  Actinomycosis  and  its  parasite.  See  Annates  de  medicine 
veterinaire,  1890. 


270  Manual  of  Veterinary  Microbiology. 

central  zone  with  the  fihaments  of  which  they  become 
continuous. 

The  thickness  of  the  peripheral  zone  is  quite  uni- 
form whatever  may  be  the  size  of  the  actinomyces 
itself,  but  it  may  be  unequal  in  the  different  parts  of 
the  same  colony  on  account  of  the  varying  dimensions 
of  the  cortical  enlargements ;  the  average  length  of 
these  enlargements  is  from  15^a  to  30/i  and  breadth 
bfitol/i,  but  these  limits  may  be  much  surpassed; 
we  have  seen  some  which  measured  74//  in  length  by 
10/i  in  thickness. 

The  club-shaped  enlargements  may  be  simple  or 
branching,  and  branching  may  take  place  either  from 
the  slender  pedicle  or  from  the  enlarged  part  itself; 
the  branches,  emerging  in  this  manner,  may  them- 
selves divide  giving  rise  to  new  club-shaped  sw^ell- 
ings,  so  that  the  whole  obtains  a  more  or  less  dense 
arborescent  appearance.  These  club-shaped  enlarge- 
ments are  composed  of  a  resistant  membrane  and 
clear  contents ;  occasionally  the  membrane  shows 
circular  depressions  which  seem  to  divide  the  body 
into  small  cubical  elements,  and  at  these  points  trans- 
verse division  is  readily  j)roduced. 

Besides  the  typical  actinomyces  just  described 
there  are  others  which  are  quite  small  and  in  which 
the  enlargements  are  absent,  and  others,  again,  in 
which  the  filamentous  central  zone  seems  to  be  en- 
tirely transformed  into  these  club-shaped  elements. 

In  colonies  of  large  size  the  central  zone  contains 
micrococci,  appearing  like  small  round  points  of  less 
than  1/1  in  diameter,  united  in  chains,  or,  more  fre- 
quently, in  small  irregular  masses ;  these  nests  of 
micrococci,  in  the  largest  tufts,  are  not  infrequently 


31icrohic  Diseases  Individually  Considered.       271 


found  in  large  numbers,  their  nature  being  more 
easily  recognized  by  the  rarefaction  of  the  mycelial 
felt-work  in  these  situations. 

Fig.  14. 


Tuft  of  Actinomyces. 
(From  Kitt's  Baderienkunde.) 


Isolated  clubs  of  Actino- 
myces.    (Johne.)     Do. 


MM.  Cornil  and  Babes  have  described  a  special 
condition  of  the  filaments  of  the  periphery  of  the 
colonies,  in  which  they  terminated  by  various  slight 
enlargements  bearing  conidia. 

Harz  classes  the  actinomyces  with  the  hyphomy- 
cetes  fungi,  regarding  it  as  a  complete  fungus  com- 
posed of  mycelia,  hyphse  and  spores,  the  -mycelium  be- 
ing represented  by  a  basal  cell  from  which  spring  the 
hyphce — the  branching  filaments  of  the  internal  zone — 
and  these  bearing  the  spores  or  enlargements  at  the 
periphery. 

The  basal  cell  of  Harz  has  not  been  found  by  other 
investigators ;  most  of  these,  however,  agree  in  re- 
garding the  enlargements  as  spores  or,  rather,  as 
sporangia ;  hence  these  enlargements  have  received 
the  name  of  conidia. 

The  classification  of  the  actinom^-ces  with  the  fungi 
appears  to  us  to  be  supported  only  by  the  results  of  the 


272  3Ianual  of  Veterinary  Microbiology. 

examination  of  this  parasite  in  the  tumors  to  which 
it  gives  rise. 

Bostroem  classes  it  with  the  group  of  schizomy- 
cetes  and  especially  with  the  cladothrix,  a  conclusion 
which  is  forced  upon  us  from  a  study  of  the  parasite 
in  its  cultures,  and  one  to  which  our  own  researches 
have  led  us.  We  are  also  inclined  to  regard  the  mi- 
crococci, spoken  of  above,  as  spores. 

The  actinomyces  is  anaerobic  and  facultatively 
aerobic. 

Action  of  physical  and  chemical  agents. — According 
to  Domec,  the  filaments  are  killed  in  five  minutes  by 
moist  heat  at  60°,  whilst  the  spores  resist  for  that 
length  of  time  a  temperature  above  60°  but  below 
75°.  This  feeble  resistance  of  the  spores  compared 
with  that  of  the  spores  of  bacteria  has  been  advanced 
as  an  argument  in  favor  of  regarding  these  spores  as 
allied  to  those  of  the  mucediuese,  and  of  classifying 
the  parasite  with  this  group  of  plants. 

The  action  of  chemical  agents  has  been  little 
studied.  Iodine  has  been  recommended  for  the  de- 
struction of  the  actinomyces  in  the  tumors,  but  the 
hot  iron  is  still  the  means  most  to  be  recommended 
for  this  purpose  when  it  is  possible  to  use  it. 

Research  and  coloration. — The  examination  of  the 
actinomyces  fungus  Is  extremely  simple,  the  suspected 
material  merely  requiring  to  be  spread  upon  a  glass 
slide;  the  hard,  yellow  grains  which  to  the  naked 
eye  have  the  appearance  of  grains  of  sand,  separate 
themselves  during  the  operation.  These  grains  are 
the  colonies  of  the  actinomyces.  To  verify  this  it  is 
merely  necessary  to  put  on  a  cover  glass  and  examine 
with  the  microscope ;  a  magnification  of  from  two  to 


Microhic  Diseases  Individually  Considered.       273 

three  hundred  diameters  will  always  prove  sufficieut 
for  the  recognition  of  the  parasites. 

This  mode  of  preparaton,  however,  is  inadequate 
for  the  detailed  study  of  the  fungus.  The  center  of 
the  radiating  masses  is  nearly  always  calcified,  and 
this  transformation  conceals  its  filamentary  structure 
and,  at  the  same  time,  prevents  the  dissociation  of  the 
tuft.  The  latter  is  also  enveloped  by  a  mucoid,  viscid 
substance  which  tends  to  hold  together  the  enlarge- 
ments at  the  periphery.  The  inconvenience  arising 
from  these  two  circumstances  is  obviated  by  treating 
the  substance  to  be  examined  with  alkalies  or  dilute 
acids. 

For  this  purpose  we  have  found  the  employment 
of  dilute  ammonia  quite  satisfactory ;  the  sand-like 
grains  yet  require  to  be  crushed  in  order  to  spread,  or 
better,  to  dissociate  them. 

By  this  means  beautiful  preparations  are  obtained 
in  which  the  mycelium  and  its  connection  with  the 
conidia  can  be  studied. 

The  examination  of  sections  is  highly  instructive. 
The  actinomyces  can  be  stained  in  diiierent  ways. 
According  to  the  way  which  is  mostly  recommended, 
the  sections  are  immersed  in  a  solution  of  orseille,(l) 
then  in  alcohol,  and,  finally,  in  an  aqueous  solution 
of  gentian  violet  or  methylene  blue.  A  double  stain- 
ing is  thus  obtained,  the  conidia  being  red  and  the 
mycelium  violet  or  blue. 

In  our  opinion  Weigert's  method  gives  better  re- 
sults.    The  antioomyces  take  a  violet  color  and  the 

(1)  Pure  orseille,  free  from  ammonia,  dissolved  until  a  deep  red 
color  is  produced,  iu :  acetic  acid,  5 ;  absolute  alcohol,  20 ;  water,  40. 


274  3Ianual  of  Veterinary  Microbiology. 

tissues  of  the  tumor  may  be  stained  red  by  picro- 
carmine. 

The  methyl  violet,  by  this  method,  may  act  in  two 
degrees.  When  the  preparation  has  been  exposed  to 
the  stainins:  solution  for  a  short  time  the  mvcelium 
of  the  actinomyces  is  alone  colored  violet,  when  it  has 
been  longer  exposed  mycelium  and  conidia  are  stained 
alike. 

Preparations  of  some  value  may  also  be  obtained 
by  the  employment  of  picro-carmine  alone  ;  the  fungi 
are  stained  yellow,  whilst  the  neoplasm  is  red,  but 
by  this  process  we  do  not  obtain  a  definition  of  the 
structure  of  the  parasite. 

MM.  Cornil  and  Babes  recommend  double  stainino- 
by  the  method  of  Gram  with  eosin  or  safranin. 
They  thus  obtain  a  violet  staining  of  the  central  fila- 
ments whilst  the  clubs  or  conidia  are  stainad  red. 

Cultures. — Bostroem  obtained  cultures  upon  beef 
blood-serum  and  upon  agar,  and  has  been  able  to 
convince  himself  that  the  bright  claviform  enlarge- 
ments of  the  periphery  of  the  colonies  are  incapable 
of  multiplication,  this  property  belonging  to  the  cen- 
tral filaments  alone  ;  hence,  he  proposed  classing  the 
actinomyces  with  the  schizomycetes  or  bacteria.  The 
structure  would  be  that  of  a  cladothrix  or  branching 
bacterium,  and  the  swollen  productions  of  the  corti- 
cal zone  only  incidental  forms  developing  when  the 
parasite  finds  itself  under  special  conditions  of  nutri- 
tion. 

We  have  cultivated  the  actinomyces  in  alkaline 
bouillons  and  our  researches  have  led  us  to  the  same 
conclusions.  Inoculation  of  peptonized  gl3'cerin- 
bouillon  with  a  particle  of  tumor  produces  a  devel- 


Microhic  Diseases  Indicidaalhj  Considered.      275 

opment  already  well  marked  at  the  end  of  the  first 
day;  at  this  time  may  be  seen  a  viscid,  coherent  layer 
floating  near  the  bottom  of  the  nutrient  fluid  which 
is  still  perfectly  limpid,  although  holding  in  suspen- 
sion a  few  white  or  yellowish,  irregularly  shaped 
grains.  In  examining  these  last  under  the  micro- 
scope, they  are  found  to  be  composed  of  ramified 
filaments,  a  few  of  which  bear  one  or  more  distinct 
enlargements  in  every  respect  similar  to  the  conidia 
of  the  cortical  zone  of  the  actinomyces.  This  struc- 
ture is  very  evident,  the  mycelial  filaments  being  yet 
loosely  intermingled.  Each  of  the  latter  consists  of 
a  tube  containing,  from  point  to  point,  a  rounded 
nucleus  which  has  a  well  marked  afiinity  for  the 
aniline  colors.     The  bouillon  acquires  a  fetid  odor. 

On  the  following  days  the  pullulation  continues 
with  great  activity,  but  the  culture  changes  its  ap- 
pearance after  the  third  day;  the  slimy  growth  in  the 
bulbs  resolves  itself  into  a  cloud  of  very  fine  granules 
which  fall  to  the  bottom  of  the  bouillon  as  if  the  mu- 
coid substance  which  held  them  suspended  had 
disappeared;  at  the  same  time,  the  two  layers  of  the 
liquid,  up  till  now  clearly  defined,  spontaneously  mix 
themselves. 

In  examining  bouillon  cultures  with  the  micro- 
scope, after  the  third  day,  the  claviform  enlargements 
are  no  longer  to  be  seeu.  The  small  white  granules 
deposited  at  the  bottom  of  the  bulbs  are  found  to  be 
composed  solely  of  fine  filaments,  presenting  lateral 
ramifications  more  abundantly  than  in  the  preceding 
preparations,  and  showing  always  in  their  interior 
the  rounded  nuclei,  placed  at  regular  intervals; 
these  mycelial  tubes  are  united  in  felted  balls  from 


276  llanual  of  Veterinary  Microbiology. 

which  some  filaments  separate  themselves  to  extend 
outward,  or  they  form  small  tufts  the  branches  of 
which  radiate  around  a  certain  point  in  one  of  these 
filaments.  Besides  these  groups  of  filaments  a  few 
may  be  observed  which  seem  detached,  but  which 
have  the  same  structure  and  are  also  branched. 

We  have  succeeded  in  obtaining  several  genera- 
tions of  these  cultures,  starting  from  a  tumor  of  the 
ox.  We  have  also  made  cultures  with  the  products 
obtained  by  inoculating  the  disease  to  rabbits.  In 
these  last  cases  the  results  have  been  the  same,  ex- 
cept that  we  have  never  seen  any  thing  resembling 
the  conidia. 

Cultures  are  much  more  active  when  protected 
from  the  air;  the  actinomyces  is,  therefore,  Chiefly 
anaerobic.  Various  investigators  have  cultivated  the 
fungus  upon  potato ;  the  surface  of  the  latter  be- 
comes excavated  during  the  first  days,  then  covered 
with  colorless  colonies  with  irregular  surface,  which 
soon  becomes  prominent  and  powdery;  they  become 
gray  in  color,  then  yellow,  or  even  greenish  when 
exposed  to  the  light.  Domec,  in  studying  these  cul- 
tures, has  recently  come  to  the  conclusion  that  the 
actinomyces  is  a  mucedine. 

Experimental  inoculations. — Johne  has  transmitted 
the  disease  to  the  calf  and  to  the  cow  by  subcuta- 
neous, intra-peritoneal,  and  mammary  inoculation; 
Ponfick  and  Israel  have  communicated  it  to  the 
calf  and  to  the  rabbit.  We,  also,  have  inoculated 
actinomycosis  to  the  rabbit  both  with  artificial  cul- 
tures and  with  the  natural  products  obtained  from  a 
cow.  The  lesions  remained  local  in  all  cases,  and 
consisted  of   an  exhausting  suppuration   which   in- 


Microbic  Diseases  Individually  Considered.      277 

volved  the  death  of  the  subject  in  from  seven  to  ten 
days. 

Etiology  and  pathogeny. — The  actinomjces  infects 
only  the  herbivora  and  omnivora ;  hence,  the  dis- 
ease has  been  attributed  to  the  foras^e.  Johne  found 
an  identical  fungus  on  the  surface  of  husks  of  barley 
arrested  in  the  tonsils  of  a  healthy  pig.  Plana  dis- 
covered, in  a  tumor  of  the  tongue,  vegetable  debris 
along  with  the  actinomyces.  Most  writers  agree  in 
incriminating  more  especially  straw  and  barley  husks. 

The  parasites,  distributed  on  the  ground  by  diseased 
animals  readily  bring  about  the  transmission  of  the 
disease  to  healthy  animals;  Stienon  records  an  in- 
stance of  enzootic  actinomycosis  in  which  nearly  all 
the  cattle  of  the  farm  were  affected. 

Inoculation  has  also  been  successfully  performed  by 
Johne.  This  author  injected  under  the  skin  and 
within  the  abdomen  of  two  calves,  and  into  the  ud- 
der of  a  cow,  the  juice  of  a  tumor  of  the  maxilla  and 
by  this  means  produced  the  characteristic  neoplasms. 
Similar  results  have  been  obtained  by  Ponfick  and 
Israel  in  the  calf  and  in  the  rabbit.  This  last  author 
made  his  inoculations  with  the  actinomycosis  of  man  ; 
the  effects  obtained  were  the  same  as  with  the  tumors 
of  cattle.  Finally,  accidental  contamination  has 
been  established  in  persons  who  have  attended  to 
animals  affected  with  the  disease. 

The-  lesions  being  most  frequently  confined  to  some 
portion  of  the  digestive  canal,  it  is  logical  to  infer 
that  the  natural  infection  occurs  through  accidental 
solutions  of  continuity  of  the  mucosa  of  these  pas- 
sages, principally  in  the  anterior  passages  (wounds  of 
the  gums,  carious  teeth,  crypts  of  the  tonsils,  etc.) 


278  3Iaiiual  of  Veterinary  Microbiology. 

But  penetration  may  also  probably  take  place  through 
the  respiratory  tract,  the  germs  being  transported 
by  the  air,  by  foreign  bodies,  or  merely  by  the  mu- 
cus. 

Cutaneous  wounds  are  also  channels  of  introduc- 
tion of  the  parasite  (actinomycosis  of  the  testicular 
cord  in  the  horse ;  actinomycosis  of  the  leg  in  the 
same  animal  in  consequence  of  a  kick ;  subcutaneous 
abscesses  in  cattle). 

The  tumors  of  actinomycosis  {adinomycomata)  re- 
sult from  the  irritation  excited  by  the  actinomyces ; 
they  frequently  have  the  structure  of  granulomata; 
the  parasite  nearly  always  occupies  the  center  of  an 
inflammatory  nodule  which  may  readily  be  differen- 
tiated into  two  zones,  an  internal,  formedof  epithelioid 
cells,  and  a  peripheral,  containing  fusiform  and  lymph- 
oid cells  and  indicating  the  transition  to  the  con- 
densed connective  tissue  which  forms  the  frame  work 
of  the  tumor.  The  fungus  may  also  very  frequently 
be  seen  surrounded  by  a  row  of  giant  cells.  This 
structure  resembles  that  of  the  tubercle  type  and 
shows  that  the  pathogenic  action  of  the  actinomyces 
consists  in  a  circumscribed  and  chronic  irritation  of 
the  tissues  into  which  it  has  been  carried.  After 
these  tumors  become  softened  in  the  center  they  con- 
tain a  puriform  yellowish  or  white  liquid  in  which 
are  suspended  yellow  grains,  most  frequently  hard 
and  calcified;  these  grains  are  the  actinomyces. 
When  the  softening  is  regular  the  tumor  acquires  a 
characteristic  spongy  appearance. 

It  may  happen,  and  this  is  the  rule  in  man,  that 
the  actinomycotic  tumors  become  complicated  with 
suppuration.     It  appears  to  be  established  that  the 


Microbic  Diseases  Individually  Considered.      279 

formation  of  pus  should  be  attributed  to  the  acti- 
nomjces  themselves  and  not  to  pyogenic  bacteria  as- 
sociated with  them.  Without  excluding  in  all  cases 
the  intervention  of  the  hitter  w.e  think  that  the  pres- 
ence or  absence  of  suppuration  may  be  dependent 
upon  the  animal  species  infected,  as  well  as  on  the 
tissue  invaded.  Thus,  the  injection  of  pure  cultures 
of  actinomyces  within  the  abdomen  of  the  rabbit 
always  occasions  a  suppurative  peritonitis;  in  man, 
also,  the  tendency  to  suppuration  is  always  very 
marked.  Stienon  records  an  instance  of  cattle  af- 
fected with  subcutaneous  abscesses  of  an  actinomy- 
cotic nature. 

The  tissue  of  the  organ  in  which  the  tumor  de- 
velops  shows  alterations  corresponding  to  the  chronic 
inflammations  set  up  by  its  presence  ;  certain  parts 
become  hypertrophied,  whilst  others  diminish  or  may 
even  disappear.  Thus  are  explained  the  fibrous  in- 
duration of  some  of  these  tumors,  the  osseous  stalac- 
tites which  develop  on  the  maxilla  when  the  invasion 
begins  in  the  periosteum,  and  the  cavities  into  which 
the  same  bone  becomes  hollowed  when  the  path- 
ological process  takes  place  in  its  center. 

Lesions  may  appear  in  the  neighborhood  of  the 
first  affected  part ;  tbey  result  from  the  progressive 
enlargement  of  the  primary  tumor,  or  from  a  vascu- 
lar emigration  of  the  fungus. 

The  gradual  increase  in  size  of  the  neoplasm  may 
lead  to  its  extension  to  the  skin  or  may  give  rise  to 
distension,  thinning,  and  perforation  of  the  latter  in 
one  or  more  points,  from  which  protrude  fungus-like 
growths  which  ulcerate  and  secrete  pus  mixed  with 
the  yellow,  pathognomonic  grains. 


280  Manual  of  Veterinary  Microbiology. 

The  lymphatic  vessels  may  convey  the  parasite  to 
the  corresponding  glands  and  the  latter  then  become 
the  seat  of  new  tumors. 

The  blood  vessels  sometimes  transport  the  fungus, 
as  has  been  established  in  man,  in  consequence  of  the 
ulceration  of  the  jugular  vein  in  contact  with  a  dis- 
eased focus. 

Generalization  does  not  appear  to  take  place  in  ani- 
mals, perhaps  on  account  of  the  premature  slaugliter 
of  the  subjects,  a  course  which  is  most  frequently 
followed  and  which  is  the  most  economical.  Acti- 
nomycosis has,  however,  been  encountered  in  the 
spleen  in  cattle  and  in  the  muscles  in  pigs.* 

Besides  the  functional  disturbances  to  which  they 
give  rise  (disturbances  of  mastication,  deglutition, 
respiration,  etc.)  the  actinomycomata,  especially  when 
they  have  ulcerated,  cause  a  progressive  emaciation 
of  the  diseased  animals. 

Botryomycosis. 
In  certain  indurations  of  the  testicular  cord  of  the 
castrated  horse  a  special  parasite  is  found  to  which 
the  various  names  of  botryomyces  (Bollinger),  dis- 
comyces  (Rivolta),  botryococcus  ascoformans  (Kitt),  etc., 
have  been  given.  It  has  also  been  met  with  in  cer- 
tain forms  of  fistulous  withers,  in  tumors  at  the  point 
of  the  shoulder,  and  in  certain  nodosities  of  the  skin 
and  subcutaneous  tissue,  etc.     Czoker  has  also    re- 

*  [The  actinomyces-like  parasite  found  in  the  muscles  of  swine 
(Actinomyces  musculorum  suis)  is  not  identical  with  the  Acti- 
nomyces bovis  sive  hominis.  C  Giinther;  Bakteriologie,  p. 
327— D.] 


Microhic  Diseases  Individually  Considered.      281 

corded  its  occurrence  in  tlie  pus  of  a  chronic  mam- 
mitis  in  the  cow. 

The  parasite  appears  in  the  form  of  a  cluster  of 
small   spheres   full    of  micrococci.  j,.^  ^^ 

The  latter  are  united  by  a  gelatinous 
substance,  and  each  of  the  spheres 
is  inclosed  by  a  double  contoured 
membrane.  JSTew  spheres  develop  .^ 
at  the  periphery  of  the  colony.  The 
parasite  is  related  to  the  genus  as- 
COCOCCUS.  Botryococcus  asco- 

Staining  mav  be  obtained  by  the  f«^™^"«-       Slightly 
"         "  .         ''  magnified.     (Kitt.) 

method  of  Gram,  with  eosm  as  con- 
trast stain.     The  eosin  becomes  fixed  especially  on 
the  gelatinous  fundamental   substance ;    picric   acid 
has  a  similar  action. 

The  pathogenesis  of  the  lesions  (botryomycomata, 
mycofibromata,  mycodesmoides)  is  the  same  as  that 
of  the  actinomycomata.  They  are  inflammatory 
tumors  of  slow  evolution  showing  a  mixture  of 
granulation  tissue  and  fibrous  tissue  of  diflferent  de- 
grees of  condensation.  The  granulation  tissue  is 
often  arranged  in  tuberculiform  masses  of  which  the 
parasite  occupies  the  center,  and  the  elements  of 
which  may  suppurate,  become  necrosed,  and  give  rise 
to  fistulous  tracks. 

The  parasite  generally  confines  its  ravages  to  its 
primary  seat ;  it  may,  however,  migrate  toward  the 
lymphatic  glands  and  may  even  pass  into  the  blood. 
Metastatic  foci  then  appear,  commonly  localized  in 
the  lung,  skin,  etc.  In  the  lung  these  lesions  have  a 
resemblance  to  those  of  glanders. 
24 


282  Manual  of  Veterinary  Microbiology. 

The  germ  gains  entrance  to  the  system  through 
operative  (castration)  or  accidental  wounds. 

Bovine  farcy. 

This  disease  is  peculiar  to  the  bovine  species. 
Formerly  noticed  in  France,  it  appears  to  be  much 
rarer  at  the  present  time ;  it  exists  in  the  Guadalope. 
It  is  usually  located  on  the  limbs,  manifesting  itself 
by  painless  cords  along  the  course  of  the  subcuta- 
neous veins  and  terminating  at  the  corresponding 
lymphatic  glands ;  the  brachial,  prescapular  and  pre- 
pectoral  glands  are  those  most  frequently  attacked. 
These  cords  and  glands  may  suppurate;  the  suppura- 
tion is  always  slowly  evolved  and  the  whole  assumes 
the  characters  of  a  cold  abscess,  with  very  thick  and 
indurated  walls.  After  these  abscesses  are  opened 
the  subject  seems  to  recover,  but  very  soon  other  tu- 
mors appear.  The  animal  pines  away  and  dies  by  slow 
decline.  The  autopsy  brings  to  light  pseudo-tubercu- 
lous lesions  wnth  purulent  centers  in  the  internal 
organs:  lungs,  liver,  spleen,  and  lymphatic  glands. 

We  are  indebted  solely  to  M.  l^ocard  for  the  bacte- 
rial study  of  the  disease. 

Microbe. — There  is  found  in  the  pus  of  the  abscesses 

and  in  the  center  of  the  pseudo-tubercular  lesions  "  a 

long,  slender  bacillus,  appearing  under 

the  form  of  small,  intricately  interwoven 

^LllY^      masses,   the   central    part     forming    an 

n  /^      opaque   nucleus   from  which   radiate  to 

Bovine  farcy,    the  periphery  myriads  of  fine  prolonga- 

(M.  and  L.)     tions,  the  majority  of    which    seem   to 

branch."     The  dimensions  of  this  bacillus  are  nearly 

the  same  as  those  of  the  bacillus  of  rouget. 


Microhic  Diseases  Individually  Considered.      283 

The  microbe  of  cattle  furcy  is  purely  aerobic^. 

Cultures. — Cultures  are  easily  obtained  between  30° 
and  40°.  In  bouillon  it  forms  rounded  pellicles  of  a 
dull  gray  color  and  oily  appearance,  floating  in  the 
liquid.  On  agar  and  gelatin  it  forms  small  masses 
more  or  less  regularly  rounded,  opaque,  and  thicker 
at  the  periphery  than  at  the  center.  On  potato  the 
growth  is  rapid  and  takes  the  form  of  dry  salient 
plates,  often  depressed  at  their  center. 

The  microbe  reproduces  itself  in  cultures  in  the 
form  of  star-like  masses  of  intertwining  filaments, 
and  it  is  only  at  the  periphery  that  the  bacillar  nature 
of  its  constituent  elements  can  be  recognized.  Ac- 
cording to  M,  I^ocard,  the  ramifications  observed  in 
these  masses  are  false ;  the  bacillus  divides  trans- 
versely, then  the  terminal  filament  inclines  to  a  right 
angle,  allowing  its  generator  to  continue  its  direct 
course.  The  organism,  therefore,  is  not  a  true  clado- 
thrix. 

Research  and  coloration. — The  bacillus  of  cattle  farcy 
is  easily  colored;  it  is  decolorized  by  the  reaction  of 
Gram  when  the  contact  with  the  alcohol  is  too  pro- 
longed, but  it  takes  the  double  stain  of  Weigert  per- 
fectly.    The  spores  are  stained  with  difiiculty. 

Experimeyital  inoculations. — The  disease  is  inocula- 
ble  to  cattle,  to  the  sheep  and  to  the  guinea  pig;  not 
to  the  rabbit,  cat,  dog,  nor  horse. 

As  a  result  of  intra-peritoneal  moculation  in  the 
guinea  pig  the  serous  lining  becomes  studded  with 
tuberculiform  nodules,  in  the  purulent  center  of 
which  the  characteristic  tufted  bacilli  are  contained; 
these  nodules  are  especially  abundant  in  tlie  omen- 
tum, which  itself  has  become  much  enlarged.     The 


284  Manual  of  Veterinary  Microbiology. 

abdominal  viscera  are  altered  only  in  their  serous 
covering,  the  tissue  proper  being  unafiected,  whilst 
the  thoracic  organs  are  exempt  from  lesions. 

The  injection  of  virulent  material  into  the  veins  is 
followed  by  a  generalized  pseudo-tuberculosis,  the 
bacilli  being  found  in  tufts  in  the  center  of  all  of  the 
lesions. 

In  both  cases  death  occurs  from  the  ninth  to  the 
twentieth  day.  Subcutaneous  inoculation  in  the 
guinea  pig  always  produces  a  voluminous  local  ab- 
scess ;  the  corresponding  lymphatic  glands  also  sup- 
purate and  recovery  takes  place  only  after  a  period 
of  great  emaciation,  leaving  behind  it  an  induration 
of  the  lymphatics.  Generalization  may,  however,  be 
occasionally  observed. 

Intra-vascular  inoculation  in  the  sheep  and  in  cat- 
tle also  produces  nodular  lesions  distributed  througli- 
out  the  viscera,  but  death  does  not  immediately  fol- 
low, the  disease  developing  very  slowly. 

Hypodermic  inoculation  in  the  same  animals  pro- 
duces an  abscess  which  ulcerates  on  difl'erent  occa- 
sions, seems  to  heal,  then  reappears  later,  exactly  as 
in  the  natural  disease. 

Subcutaneous  inoculation  in  refractory  animals  oc- 
casions an  abscess  which  quickly  heals. 

Tetanus. 

Tetanus  occurs  spontaneously  in  all  the  domesti- 
cated animals  and  in  man  ;  it  is  more  frequent  in  the 
horse,  ox,  sheej),  and  goat,  but  it  has  also  been  ob- 
served in  the  pig  and  dog. 

The  contagiousnesss  of  tetanus,  which  had  long 
been  suspected  from  clinical   observation,  has  been 


Microbic  Diseases  Individually  Considered.       285 

demonstrated  by  experimental  inoculation,  and  its 
causative  agent  has  been  brought  to  light  by  bacteri- 
olo2:ical  research. 

3Iicrobe.— The  bacillus  of  tetanus,  first  described 
by  ISTicolaier,  is  a  slender  rod,  measuring  S/j.  to  b/j.  in 
length,  homogeneous,  or  containing  at  one  end  an 
enlargement  in  which  appears  a  spherical  spore  of  a 
diameter  double  or  quadruple  that  of  the  filament.  It 
has,  therefore,  wheu  sporulated,  the  form  ofa  pin, 
of  which  the  brilliant,  lustrous  spore  represents  the 
head.  In  wounds  the  bacillus  sometimes  attains  a 
len<>-th  much  greater  than  that  indicated  above. 

The  bacillus  of  l^icolaier  is  motile,  Y\g.  17. 

its  movements  resembling  those  of  the       i  ^    ^    / 
septic   vibrio,   but    these    movements       *      •      *© 
cease   when    fructification   is   accom-       i        ^  . 
plished.     It  is  anaerobic,  multiplying  / 

only  when  the  atmospheric  air  is  ex-        Bacillus  of  te- 

.    "1     ,  .  f.    T        ,  1  •         tanus,   sporula- 

cluded.      A    rarefied    atmosphere   is,     ^^^    ^^^    ^^^_ 

however,  compatible  with  its  vitality,     sporulated.  (M. 

and  this  will  account  for  its  mutlipi-     and  L.) 

cation  in  free  media,  the  aerobic  germs  protecting  it 

from  contact  with  too  large  a  proportion  of  oxygen. 

The  tetanus  bacillus  remains  intrenched  in  the  in- 
fected focus  and  does  not  penetrate  into  the  blood 
during  life;  at  the  approach  of  death,  or  a  certain 
time  after  death,  it  may  be  found  in  remote  parts  in 
which  the  deoxygenation  of  the  blood  has  allowed  of 
its  multiplication. 

The  bacillus  is  met  with  in  its  two  forms,  homo- 
geneous and  sporulated,  in  the  pus  of  wounds  which 
have  given  rise  to  tetanus,  the  sporulated  form,  how- 
ever, being  less  abundant  than  the   non-sporulated. 


286  Manual  of  Veterinary  Mlcrohiology. 

In  young  cultures  the  latter  form  also  predomi- 
nates. 

Action  of  'physical  and  chemical  agents. — The  spores 
are  very  resistant  to  heat ;  they  support  a  tempera- 
ture of  80°  during  six  hours,  or  90°  during  one  hour. 
In  moist  heat  at  100°  they  are  killed  in  a  quarter  of 
an  hour,  at  115°  in  five  minutes.  Spores  which  are 
thoroughly  dried  retain  their  vitality  for  a  long  time 
if  protected  from  the  light.  Exposed  to  the  light 
they  do  not  survive  more  than  one  month  especially 
if,  at  the  same  time,  exposed  to  the  air. 

The  bacilli  of  Nicolaier  are  little  sensitive  to  the 
action  of  antiseptics,  notably  less  so  than  the  septic 
vibrio.  Thus,  sublimate  solution,  at  1  to  1000,  only 
kills  these  bacilli  after  three  hours;  three  per  cent 
carbolic  acid  solution  after  ten  hours.  The  spores  re- 
sist a  five  per  cent  solution  of  carbolic  acid  for  fifteen 
hours,  the  same  solution  with  an  addition  of  0*5  per 
cSnt  of  hydrochloric  acid,  two  hours,  and  1  to  1000 
sublimate  solution  with  a  like  proportion  of  hydro- 
chloric acid,  thirty  minutes.  They  are  unafltected  by 
the  gastric  juice  and  by  putrefaction;  active  cultures 
having  been  administered  to  rabbits,  guinea  pigs,  mice 
and  dogs  by  way  of  the  mouth,  all  these  animals  re- 
mained healthy,  whilst  their  excrements  were  virulent 
for  other  animals. 

Cultures. — The  bacillus  of  Nicolaier  vegetates  in 
artificial  culture  media  when  the  oxygen  of  the  air  is 
excluded  and  when  under  suitable  conditions  of  tem- 
perature; culture  vessels  should  therefore  be  em- 
ployed in  which  a  vacuum  has  been  created  or  in 
which  the  atmosphere  has  been  replaced  by  hydro- 
gen, carbonic  acid,  etc.    Solid  liquetiable  media,  such 


Microbic  l)iseases  Individually  Considered.      287 

as  gelatin  and  agar,  are  sometimes  freed  from  air  by- 
boiling  for  half  an  hour;  the  mass  is  solidified  by 
rapid  cooling,  inoculated  by  deep  puncture,  and  the 
surface  of  the  medium  covered  with  a  layer  of  ster- 
ilized oil  which  prevents  the  absorption  of  the  at- 
mospheric oxygen.  Deoxygenation  can  also  be  ac- 
complished by  the  addition  to  the  same  media  of  sub- 
stances which  readily  absorb  oxygen.  Kitasato  ad- 
vises the  addition  to  gelatin  or  agar,  of  glucose  two 
per  cent,  sulpho-indigotate  of  soda  0*1  per  cent,  blue 
turnsol  five  per  cent. 

The  most  favorable  temperature  varies  between 
38°  and  39°,  but  multiplication  still  occurs  at  18°  and 
continues  even  at  43°. 

The  natural  inoculation  substances  at  our  disposal : 
pus  of  wounds  which  have  given  rise  to  tetanus,  earth, 
forage,  etc.,  are  always  contaminated  with  other  germs 
than  those  of  this  disease  ;  hence,  impure  cultures 
are  first  obtained  from  which  the  bacillus  of  i^icolaier 
must  be  isolated.  With  this  aim  we  take  advantage 
of  the  great  resistance  of  its  spores,  and  heat  the 
sporulated  cultures  in  a  water  bath  at  80°  to  90°  for 
three  quarters  of  an  hour  to  one  hour ;  traces  of 
these  cultures  are  sowed  in  anaerobic  tubes  which  are 
then  closed  over  the  flame  and  the  gelatin  spread  out 
on  their  walls  by  a  rotatory  motion. 

The  colonies  which  then  develop  are  composed  ex- 
clusively of  tetanus  bacilli,  as  may  be  proved  by  in- 
oculation. If  some  spores  of  the  septic  vibrio  have 
resisted  the  heat  and  produced  a  collateral  vegetation, 
we  should  then  resort  to  the  action  of  antiseptics ; 
1  to  1000  sublimate  solution  kills  the  tetanus  bacillus 


288  Manual  of  Veterinary  Microbiology. 

only  after  three  hours,  3  per  cent  carbolic  solution 
only  after  two  hours.     (Sanchez-Toledo.) 

In  bouillon  the  development  is  very  rapid ;  the 
liquid  becomes  turbid  in  one  day  and  sets  free  small 
bubbles  of  gas  ;  the  growth  abates  and  becomes  de- 
posited toward  the  fifteenth  day. 

When  a  gelatin  tube  is  inoculated  by  deep  punc- 
ture and  kept  at  18°,  the  growth  forms,  after  four  or 
five  days,  small  cloud-like  points  from  which  fine  lines 
radiate  perpendicular  to  the  puncture.  The  culture 
has  a  floculent  appearance,  slowly  fluidifies  the  gela- 
tin, and  bubbles  of  gas  are  disengaged;  when  the 
gelatin  is  entirely  fluidified  the  culture  is  deposited 
in  the  form  of  white  flakes. 

Cultures  upon  agar  are  less  characteristic.  Growth 
also  takes  place  upon  serum  and  potato.  Cultures 
of  tetanus  emit  a  smell  of  burnt  horn  and  produce 
various  gases,  including  carbonic  acid  and  hydro- 
carbons. 

Research  and  coloration. — The  bacillus  of  tetanus  is 
easily  stained  with  the  aniline  colors  ;  it  takes  the 
Gram  very  well  and  appears  as  a  slender  rod,  uniform 
in  size  or  swollen  at  one  of  its  extremities.  Before 
the  formation  of  the  spore  this  enlargement  stains 
like  the  filament  itself.  The  spores  are  not  stained 
by  this  process  but  may  be  colored  by  the  method 
usually  employed  for  the  staining  of  spores. 

Experimental  inoculations. — The  disease  is  inocula- 
ble  to  the  smaller  animals  and  notably,  with  a  sus- 
ceptibility decreasing  in  the  order  in  which  they  are 
named,  to  the  mouse,  white  rat,  guinea  pig,  rabbit,  dog, 
pigeon  and  chicken.  The  mouse,  white  rat  and  guinea 
pig  are  extremely  susceptible,  0.002  cub,  cent,  being 


Microbic  Diseases  Individually  Considered.      289 

sufficient  to  produce  in  these  animals  the  typical  dis- 
ease with  fatal  results  iu  36  to  40  hours.  The  rabbit 
requires  10  to  30  drops  ;  the  symptoms  appear  from 
the  second  to  the  third  day  and  death  occurs  four  to 
ten  days  later.  The  dog,  pigeon  and  chicken  are 
less  susceptible  and  sometimes  survive  large  doses. 

The  inoculation  succeeds  well  in  the  connective 
tissue,  in  the  peritoneum  and  in  the  arachnoid.  In 
the  connective  tissue  it  causes  -an  cedematous  swell- 
ing, the  contractions  appearing  first  of  all  in  the  ad- 
jacent muscles.  When  inoculated  in  the  peritoneum 
or  in  the  blood  these  appear  similtaneously  in  all 
parts  of  the  body.  The  disease  is  not  pro.duced  either 
by  inhalation  or  ingestion  of  virulent  products. 
Ingestion  of  tetanic  toxines  is  also  without  effect, 
these  toxines  being  destroyed  by  the  digestive  juices. 

According  to  the  dose  inoculated  and  the  suscepti- 
bility of  the  animals  the  experimental  disease  may  be 
acute  or  chronic,  fatal  or  curable. 

In  connection  with  experimental  inoculations  three 
cases  must  be  distinguished.  The  material  to  be  in- 
jected may  consist  of  the  entire  culture,  of  the  amor- 
phous part  alone  freed  from  its  microbes  by  filtration, 
or,  finally,  of  the  microbes  alone  deprived  of  their 
soluble  products  by  filtration,  lixiviation,  or  heat. 

In  the  first  two  cases — inoculation  of  the  entire 
culture  or  of  its  soluble  products — the  classic  disease 
is  reproduced.  In  the  last  case,  according  to  MM.Vail- 
lard  and  Vincent,  the  inoculation  remains  without  ef- 
fect except  when  excessive  doses  are  employed.  The 
tetanus  bacillus,  therefore,  appears  to  be  unable  to 
multiply  in  the  organism  in  the  absence  of  its  toxines, 
25 


290-  Manual  of  Veterinary  Microbiology. 

being  destroyed,  in  such  case,  by  the  phagocytes ;  it 
excites  an  active  diapedesis  which  may  be  observed 
after  injections  into  the  anterior  chamber  of  the  eye. 
The  toxines  of  cultures,  on  the  other  hand,  seem  to 
repel  the  leucocytes  and  thus  protect  the  microbes 
from  their  destructive  action.  Certain  other  sub- 
stances may  take  the  place  of  this  action  :  inoculation 
of  spores  alone  is  followed  by  tetanus  when  lactic 
acid,  diluted  to  1  to  500,  or  trimethylamin,  is  injected 
at  the  same  time,  or  when  a  contusion  is  produced  in 
the  inoculated  tissues.  Simultaneous  injection  of  the 
germs  of  tetanus  and  the  micro-bacillus  prodigiosus 
also  allows  the  irruption  of  the  disease;  the  prodigio- 
sus attracts  the  phagocytes  to  itself  and  thus  forms  a 
barrier  behind  which  the  tetanus  bacillus  multi[)lies 
and  secretes  its  protective  toxines. 

The  experiments  of  Yaillard  and  Yincent  have  been 
repeated  by  Sanchez-Toledo,  who  seems  to  have  suc- 
ceeded in  transmitting  the  disease  by  means  of  cult- 
ures freed  from  their  toxines  and  from  all  adjuvant 
substances. 

Etiology  and  pathogeny. — The  tetanus  bacilli  or  their 
spores  exist  in  the  soil ;  the  disease  has  often  been 
produced  by  inoculation  of  water  with  which  certain 
specimens  of  soil  have  been  washed.  From  the  soil 
they  are  transported  in  the  dried  forage,  pass  un- 
changed through  the. digestive  canal  of  herbivora  and 
with  the  manure  are  returned  to  the  soil.  By  inocu- 
lations they  have  been  demonstrated  in  hay  and  in 
the  excrements  of  healthy  horses  and  cattle.  Tetanus 
is  therefoi^e  of  telluric  origin;  but  it  can  also  be  trans- 
mitted from  one  animal  to  another,  either  directly  or 
indirectly.    The  microbe  being  inactive  when  inhaled 


Microhic  Diseases  Individually  Considered.      291 

or  ingested,  it  must  gain  entrance  to  the  system 
through  a  solution  of  continuity. 

All  wounds  are  not  alike  adapted  to  the  growth  of 
the  tetanus  bacillus ;  the  germ  is  anaerobic  and  conse- 
quently requires  a  medium  little  accessible  to  atmos- 
pheric air;  besides,  it  is  inofiensive  if  not  protected 
against  the  phagocytes  by  accessory  conditions.  The 
production  of  tetanus,  therefore,  as  a  rule,  requires 
deep,  anfractuous,  contused  wounds  or  those  contami- 
nated by  other  germs,  and  more  especially  by  the 
ordinary  pyogenic  species.  Nevertheless,  tetanus  has 
often  been  observed  to  follow  insignificant  wounds. 
It  should  be  observed  that  wounds  favorable  for  the 
growth  of  the  bacillus  of  tetanus  are  also  favorable 
for  that  of  the  septic  vibrio.  Now,  the  bacillus  of 
malignant  oedema  is  also  found  in  tetanogenic  earth, 
so  that  the  same  wound  may  be  contaminated  with 
both  germs;  gangrene,  however,  running  its  course 
more  rapidly  than  tetanus,  the  latter  may  only  appear 
after  recovery  from  the  former,  or  may  not  appear 
at  all  if  the  subject  succumbs  to  the  septicaemia 
(Verneuil). 

The  bacillus  of  tetanus  secretes  in  the  wound  spe- 
cial toxines  which  have  a  poisonous  action  on  the 
organism  similar  to  that  of  strychnine.  If  a  culture 
of  tetanus  be  tiltered  so  as  to  completely  separate  the 
microbes  from  the  soluble  part,  and  the  latter  be  in- 
jected to  animals,  an  absolutely  typical  tetanus  re- 
sults. This  filtered  liquid  is  very  toxic  :  one-twentieth 
of  a  drop  kills  a  mouse  in  thirty-six  hours,  one  drop 
kills  a  guinea  pig  in  twenty- four  hours. 

The  nature  of  the  tetanic  poison  is  yet  incom- 
pletely known  in  spite  of  numerous  investigations. 


292  Manual  of  Veterinary  Microbiology. 

Brieger  isolated  from  impure  cultures  on  meat  several 
toxic  ptomaines:  tetanin,  tetanotoxin  and  spasmatoxin. 
The  first  gives  the  typical  tetanus  when  injected  in 
very  small  doses,  the  second  produces  tonic  and  clonic 
convulsions,  and  the  third  hyper-salivation  and  con- 
vulsions. According  to  more  recent  investigations 
the  tetanic  poison  appears  to  be  an  albumin  related 
to  the  diastases  or  soluble  ferments.  It  is  destroyed 
by  a  temperature  of  65°  in  five  minutes,  is  insoluble  in 
alcohol,  soluble  in  water,  and  adheres  to  precipitates 
of  alumina  and  phosphates.  It  is  destroyed  by  heat 
and  preserved  by  desiccation  if  this  is  rapidly  ob- 
tained in  a  vacuum  and  without  the  aid  of  heat. 

This  toxine  appears  to  act  more  particularly  on  the 
muscular  tissue,  which  would  explain  the  appearance 
of  the  first  tetanic  contractions  in  the  muscles  which 
are  adjacent  to  the  wound  or  to  the  place  of  inocula- 
tion. When  administered  by  way  of  the  digestive 
canal  it  is  inactive. 

From  the  preceding  considerations  it  may  be  in- 
ferred that  the  microbe  of  Nicolaier  produces  its  ef- 
fects only  by  means  of  the  diastases  which  it  secretes. 
Moreover,  it  gains  entrance  into  the  blood  only  in 
the  last  moments  of  life,  or  after  death. 

Attenuation.  Vaccinations. — By  heating  the  filtrate 
to  different  temperatures  between  55°  and  100°  until 
it  becomes  inactive,  and  inoculating  this  material  to 
mice,  we  determine  a  mild,  curable  form  of  tetanus, 
but  one  which  is  not  followed  by  immunity. 

Kitasato  endeavored  to  obtain  immunity  against 
tetanus  by  the  action  of  trichloride  of  iodine.  He 
injected  0-3  cc.  of  filtered  culture  under  the  skin  of  a 
rabbit  and  immediately  afterward,  in  the  same  place, 


Microblc  Diseases  Individually  Considered.      293 

3  cc.  of  1  per  cent  solution  of  trichloride  of  iodine, 
the  latter  injection  being  repeated  every  twenty-four 
hours  until  the  rabbit  had  received  in  all  0-15  grams 
of  the  trichloride.  If,  after  fourteen,  eighteen,  twenty- 
five  days,  2  cc.  of  the  \irulent  filtrate,  or  2  to  3  cc.  of 
virulent  bouillon  culture,  be  injected,  the  tetanic 
symptoms  which  supervene  disappear  in  a  few  days 
and  the  animal  can  then  receive  an  injection  of  5  cc. 
of  virulent  culture  without  manifesting  any  symp- 
toms. The  rabbit  is  therefore  vaccinated;  but  this 
process  is  inconstant,  and  sixty  per  cent  of  the  rabbits 
do  not  obtain  immunity.  The  mouse  and  guinea  pig 
do  not  obtain  it  at  all.  Now,  the  serum  and  blood 
of  these  vaccinated  rabbits  possess  the  very  interest- 
ing property  of  destroying  the  toxine;  they  are  toxin- 
icidal.  A  mixture,  twenty-four  hours  old,  of  1  cc.  of 
a  virulent  culture  with  5  cc.  of  this  serum  can  be  in- 
jected with  impunity  to  mice.  It  is  even  possible 
by  means  of  this  serum  to  check  the  disease  experi- 
mentally developed  in  the  mouse.  Further,  the  in- 
jection of  0-2  to  0-5  cc.  of  this  serum  into  the  peri- 
toneum of  the  mouse  confers  an  immunity  of  from 
forty  to  fifty  days'  duration. 

Tizzoni  and  Cattani  have  obtained  immunity  in  the 
dog  and  pigeon  by  the  injection  of  progressive  doses 
of  cultures  of  gradually  increasing  virulence.  The 
serum  of  the  dog,  thus  vaccinated,  is  toxinicidal  and 
confers  immunity  on  the  dog  and  on  the  mouse  but 
not  on  the  rabbit  or  guinea  pig,  and  does  not  check 
the  disease  when  already  established.  These  authors 
have  isolated  and  obtained  in  the  dry  state  the  tox- 
inicidal product  of  the  serum  {antitoxin);  they  appear 


294  31anual  of  Veterinary  Microbiology. 

to  have  successfully  used  it  in  the  treatment  of  human 
tetanus. 

Vaillard,  by  injecting  into  the  blood  of  rabbits, 
first,  in  several  doses,  40  cc.  of  filtered  culture  heated 
to  58°,  second,  10  cc,  of  filtered  culture  heated  to  51°, 
and,  finally,  15  cc.  of  filtered  culture  not  heated,  did 
not  immunize  these  animals,  but  communicated  to 
their  blood  the  toxinicidal  power;  hence  it  follows 
that  there  is  no  relation  between  the  toxinicidal 
property  and  the  refractory  state.* 

*  [Of  the  more  recent  investigations  bearing  on  the  etiology  of 
tetanus  and  the  production  of  immunity,  the  following  points 
may  be  briefly  noted : 

The  necessary  co-operation  of  other  microbes  at  the  place  of  in- 
fection (in  the  naturally  acquired  disease)  has  been  reaffirmed. 
(Vaillard  and  Rouget.) 

According  to  Courmont  and  Doyon,  the  special  tetanus  toxine 
results  from  a  fermentation  excited  in  certain  tissues  of  the  or- 
ganism by  a  soluble  ferment  secreted  by  the  bacillus  tetani. 
{Compt.  rend.  Soc.  cle  Blologie,  March,  1893.) 

Immunity  can  be  obtained  by  repeated  injection  of  cultures  of 
the  bacillus  tetani  grown  in  bouillon  prepared  from  the  thymus 
gland  of  calves,  or  of  filtered  cultures  to  which  a  certain  propor- 
tion of  an  extract  of  this  gland  has  been  added  (Brieger,  Kitasato, 
etc.) ;  the  blood  serum  of  animals  thus  immunized  possesses  im- 
munizing properties.  By  repeated  injection  of  gradually  increas- 
ing doses  of  virulent  cultures  to  animals  (rabbits,  dogs,  horses) 
which  have  been  thus  immunized,  the  protective  power  of  the 
serum  of  these  animals  becomes  greatly  increased.  This  serum 
then  furnishes  an  effective  "  vaccine."  The  serum  of  such  im- 
munized animals  or  a  preparation  from  the  same  (anti-toxin  :  Tiz- 
zoni,  Cattani)  has  been  used  (by  repeated  subcutaneous  injection 
of  considerable  doses)  in  the  treatment  of  tetanus  in  man,  and 
apparently  with  good  results.  (Ref.  Centralhl.  f.  Bacteriologie,  XIII, 
4,14;  XIV,  A,  12,  19;  XV,  A.) 

The  curative  action  of  the  serum  of  immunized  animals  de- 
pends upon  its  immunizing  properties ;  it  localizes  the  tetanus 


Microbic  Diseases  Individually  Considered.      295 

Diphtheria. 

In  its  widest  meaning  this  term  is  applied  to  a 
special  form  of  inflammation  of  the  integuments  in 
which  a  concrete  exudate  is  produced  in  the  thick- 
ness of  the  derm  and  involves  its  mortification ;  this 
exudate  is  called  diphtheritic.  "When  the  fibrinous 
deposit  is  limited  to  the  epithelium  the  inflammation 
is  said  to  be  croupous.  These  two  forms  of  inflamma- 
tion can  be  produced  by  very  varied  causes :  these 
are  mechanical  (compression),  or  physical  (burns),  or 
chemical  (caustics),  or,  finally,  biological  (parasites 
and  microbes).  Among  the  number  of  parasites  may 
be  mentioned  the  gregarinse  of  the  contagious  epi- 
thelioma of  poultry  and  the  coccidia  of  typhlitis  of 
the  same  animals;  among  microbes  a  large  number 
possess  the  same  faculty ;  of  these  we  need  only  re- 
call the  diphtheritic  exudates  of  pneumo-enteritis  of 
the  pig,  of  acute  glanders,  and  of  petechial  typhus, 
etc.  Diphtheria  of  wounds,  or  hospital  gangrene, 
characterized  by  a  superficial  necrosis  of  the  divided 
tissues,  must  also  be  attributed  to  the  contamination 
of  the  latter  by  micro-organisms. 

From  a  clinical  point  of  view  the  term  diphtheria  re- 
fers to  a  specific  disease  due  to  a  special  germ,  and 
manifesting  itself  by  an  inflammation,  with  croupous 
or  diphtheritic  evolution,  of  the  respiratory  and  some- 

by  protecting  the  parts  of  the  nervous  system  not  yet  attacked  by 
the  tetanus  poison.     (Tizzoni,  Cattani:  Id.  XV,  17.) 

Tests  of  the  curative  action  of  the  serum  of  immunized  animals 
made  by  Nocord,  in  the  case  of  two  sheep  artificially  infected 
with  tetanus,  resulted  unfavorably.  (Ref.  Jour.  Comp.  Path.  VII, 
l.)-D.] 


296  Manual  of  Veterinary  Microbiology. 

times  digestive  mucous  membrane.  This  disease 
has  been  thoroughly  studied  in  man  ;  it  also  occurs 
in  certain  species  of  animals,  particularly  in  birds  and 
in  the  calf.  At  one  time  it  was  believed  that  human 
and  avian  diphtheria  were  identical,  but  this  view  is 
no  longer  entertained.  The  two  diseases  have  a 
different  evolution  and  different  microbes. 

Human  diphtheria. — Klebs  and  Loffler  discovered  in 
the  false  membranes  a  bacillus,  straight  or  curved, 
with  rounded  ends,  sometimes  club-shaped,  at  other 
times  less  than  the  average  thickness.  It  meas- 
ures 2'5/z  to  3/i  in  length  by  0-7;/  in  thickness;  it  is 
especially  aerobic  but  also  grows  when  the  air  is  ex- 
cluded; it  is  met  with  in  the  superficial  zone  of  the 
false  membranes.  The  germ  grows  on  most  of  our 
artificial  media;  it  is  stained  by  Loffler's  methylene 
blue  and  by  the  Gram  method.  Roux  and  Yersin 
have  completed  its  biological  study  ;  they  isolated  it 
by  inoculating  a  series  of  serum  tubes  without  re- 
charging the  platinum  w^ire :  the  colonies  of  diph- 
theritic bacilli  appear  as  grayish-white  rounded 
growths  with  the  center  more  opaque  than  the 
periphery. 

Excoriated  mucous  membranes,  inoculated  with  a 
culture,  soon  show  the  characteristic  false  membrane 
in  rabbits,  guinea  pigs,  cats,  pigeons,  and  chickens. 

The  subcutaneous  injection  of  a  few  drops  of  the 
liquid  kills  the  guinea  pig  in  thirty-six  hours  with 
general  vascular  dilatation  and  pleural  effusion.  The 
rabbit  requires  1  cc.  of  the  culture  and,  like  the  pigeon, 
dies  after  several  days.  The  dog  and  the  sheep  also 
succumb.  In  all  cases  a  hemorrhagic  cedema  is  pro- 
duced at  the  place  of  inoculation  and  the  vessels  of 


Microhic  Diseases  Individually  Considered.      297 

the  different  organs  are  congested.  When  death  of 
the  inocuhited  animals  is  delayed  they  exhibit  paraly- 
sis resembling  that  observed  in  the  child  suffering 
from  this  disease. 

The  bacilli  occur  only  in  the  specific  lesions;  there 
they  secret  a  poison  the  absorption  of  which  deter- 
mines the  general  symptoms  of  diphtheria.  Cultures 
freed  from  microbes  by  filtration  are  very  toxic ;  un- 
der their  influence  guinea  pigs  exhibit  a  pronounced 
dyspnoea;  rabbits  are  attacked  with  progressive 
paralysis  and  often  with  diarrhcea.  The  dog  and  the 
sheep  also  succumb  after  showing  symptons  of  paral- 
ysis. 

The  toxic  substance  of  cultures  is  a  diastase  pre- 
senting much  analogy  with  that  of  tetanus;  in  the 
digestive  canal  it  is  innocuous. 

Behring  appears  to  have  obtained  immunity  in 
guinea  pigs :  1st,  by  inoculating  them  with  cultures 
sterilized  at  65°  to  70°  C;  2d,  by  injecting  them  with 
a  mixture  of  one  part  of  trichloride  of  iodine  and 
five  hundred  parts  of  these  same  cultures ;  3d,  by  in- 
oculating them  with  the  serous  or  sanguinolent 
liquid  taken  from  the  pleura  of  guinea  pigs  dead  of 
diphtheria. 

Avian  diphtheria. — Birds  are  very  subject  to  a  dis- 
ease manifesting  itself  by  the  production  of  false 
membranes  and  diphtheritic  exudates  on -the  mucous 
membranes  of  the  mouth,  pharynx,  oesophagus,  nose, 
eyes,  larynx,  trachea,  lungs,  air  cavities,  intestines, 
and  upon  the  skin.  This  disease  is  very  contagious 
although  much  less  severe  than  that  of  man;  like  the 
latter  it  may  occasion  rapid  mechanical  asphyxia,  but 
more  frequently  it  is  protracted,  presenting  remis- 


298  Manual  of  Veterinary  Microbiology. 

sions  and  exacerbations,  and  leading  to  the  emaciation 
of  the  affected  birds.  A  catarrhal  inflammation 
which  sometimes  occurs  in  the  attacked  mucous 
membranes,  by  provoking  glairy  morbid  secretions, 
aggravates  the  cachexia  and  hastens  the  fatal  termina- 
tion. 

Lofiler  attributes  the  disease  to  a  special  bacillus, 
staining  by  the  methods  of  Gram  and  Weigert,  which 
he  met  with  in  the  fluid  products  of  the  inflamed 
mucous  membranes,  in  the  false  membranes,  the 
lesions  of  the  liver,  and  in  the  blood.  This  bacillus 
has  nearly  the  same  dimensions  as  that  of  human 
diphtheria  but  it  is  smoother  and  more  uniform  in 
thickness.  It  is  abundantly  present  in  the  superficial 
layer  of  the  false  membranes,  rare  or  absent  in  the 
deep  layers.  Along  with  this  specific  bacillus  other 
microbes  are  constantly  found  in  the  concrete  exu- 
dates. 

Lofiler  reproduced  avian  diphtheria  in  the  rabbit 
and  the  pigeon ;  death,  when  it  occurred,  supervened 
less  quickly  than  with  the  human  bacillus.  The 
guinea  pig  and  the  dog  are  also  more  sensitive  to  the 
latter  bacillus  than  to  that  of  birds.  Lofiler  culti- 
vated and  described  the  microbe  and  with  it  repro- 
duced the  disease  in  birds  and  the  rabbit  by  inoculation 
of  cultures  on  the  mucous  membrane,  on  the  skin, 
and  in  the  subcutaneous  cellular  tissue. 

The  disease  is  propagated  by  means  of  the  morbid 
matters  (discharge,  fseces,  false  membranes)  of  the  dis- 
eased animals.  The  virus  gains  entrance  into  the 
organism  of  healthy  animals  with  the  food  or  by  the 
air.  Contamination  most  frequently  takes  places  in 
an  indirect  manner  but  may  also  occur  directly.     M. 


Microbic  Diseases  Individually  Considered.      299  ■ 

Meguiii  has  recorded  an  outbreak  in  pigeons  in  which 
the  young  animals  quickly  succumbed  to  diphtheria ; 
he  attributes  the  disease  of  the  young  pigeons  to  the 
fact  that  the  mothers  were  affected  with  old,  little 
marked  oesophageal  lesions  the  virulent  products  of 
which  mingled  with  the  lactescent  liquid  of  the  crop 
were  fed  directly  to  the  young. 

The  disease  appears  in  poultry  pens  in  consequence 
of  the  importation  of  birds  coming  from  infected  cen- 
ters or  on  the  return  of  animals  which  have  been  ex- 
hibited in  bird  shows.  The  virus  appears  to  be 
preserved  for  a  considerable  time  in  contaminated 
pens  and  in  manure. 

In  spite  of  the  cases  advanced  by  different  observ- 
ers it  appears  to  be  well  established  that  the  disease 
of  fowls  is  not  transmissible  to  man. 

Diphtheria  of  calves. — There  exists  in  the  bovine 
species  a  diphtheritic  affection  transmissible  chiefly  to 
calves  and  also  having  its  origin  in  a  special  bacillus. 
It  localizes  itself  in  the  back  of  the  throat,  in  the 
trachea,  and  in  the  bronchi. 

Babies. 

Rabies  occurs,  under  natural  conditions,  in  all  do- 
mesticated animals  and  in  several  wild  species:  wolf, 
fox,  jackal,  bear,  etc.  It  is  very  much  the  most  fre- 
quent in  carnivora,  and  more  especially  in  the  dog 
and  wolf. 

Microbe. — In  despite  of  numerous  researches  con- 
cerning the  pathogenic  agent  of  rabies,  its  morpho- 
logical characters  are  yet  unknown.  Its  existence 
however  can  not  be  doubted ;  it  multiplies  in  the 
organism  to  which  it  is  inoculated,  and  loses  or  gains 


300  3Janual  of  Veterinary  31lcrobiology. 

in  virulence  like  the  well  defined  microbes  of  other 
diseases.  Fol  and  Babes  have  each  described  micro- 
cocci which  they  were  able  to  cultivate  in  bouillon, 
and  with  which  cultures  they  believed  that  they  trans- 
mitted rabies.  Babes  also  describes  a  short  bacillus. 
Mottet  and  Protopopoff  isolated  from  the  brain  very 
fine  bacteria,  cultures  of  which  in  bouillon,  according 
to  these  authors,  gave  the  typical  disease. 

Action  of  2)hysical  and  chemical  agents. — The  viru- 
lence of  an  emulsion  of  the  spinal  cord  of  a  rabid 
animal  is  dissipated  when  heated  twenty-four  hours 
at  45°,  one  hour  at  50°,  and  half  an  hour  in  steam  at 
100°. 

It  resists  a  temperature  of  — 20°  for  thirty  hours  at 
least.  It  is  destroyed  by  fourteen  hours  exposure  at 
37°  to  solar  light.  Desiccation  in  the  air  rapidly  di- 
minishes its  virulence  and  destroys  it  in  a  few  days. 

Virulence  is  retained  in  cadavers  for  several  weeks 
if  decomposition  is  prevented,  but  it  is  destroyed  by 
putrefaction.  Under  the  influence  of  1  to  1000  sub- 
limate solution,  2  or  5  per  cent  solution  of  perman- 
ganate of  potash,  or  50  per  cent  alcohol,  the  virus  is 
quickly  impaired;  15  percent  alcohol,  on  the  other 
hand,  preserves  it  intact  for  seven  days  at  least. 
Even  a  large  dose  of  the  emulsion  proves  inoffensive 
when  it  has  been  rendered  either  acid  or  alkaline. 
Perfectly  neutral  glycerin  (30  B)  preserves  its  patho- 
genic power  in  a  perfect  manner. 

Experimental  inoculations. — With  the  exception  of 
some  individuals  which  are  naturally  insusceptible, 
the  majority  of  the  mammalia  contract  rabies  when 
inoculated. 

The  species  used  in  the  laboratories  are  the  rab- 


Microbic  Diseases  Individually  Considered.       301 

bit,  guinea  pig,  dog,  ape,  rat,  and  birds.  The  last 
named  species  almost  invariably  recover  spontane- 
ously (Gibier).  The  virulent  material  is  taken  from 
the  nervous  substance  (brain,  medulla,  cord  and 
nerves),  from  the  salivary  glands,  the  saliva,  bron- 
chial mucus,  and  from  the  pancreas.  The  milk  occa- 
sionally shows  itself  virulent,  but  the  blood  is  not ; 
complete  transfusion  of  blood  from  a  rabid  dog  to  a 
healthy  subject  did  not  produce  the  disease  (Bert.) 
In  practice  we  resort  more  especially  to  the  nerve 
centers,  which  furnish  a  pure  virus;  for  use,  a  parti- 
cle is  reduced  to  pulp  and  the  latter  diluted  in  steril- 
ized water  or  bouillon  ;  in  this  way  a  white  milky 
fluid  is  obtained,  a  veritable  emulsion  of  the  nervous 
substance. 

The  inoculation  maybe  performed  in  various  ways; 
it  may  be  subcutaneous,  intra-muscular,  intra-venous, 
iutra-ocular,  intra- cranial,  intra-nervous,  etc.,  the  re- 
sult varying  according  to  the  method  employed. 

In  the  dog,  subcutaneous  and  intra-venous  inocula- 
tions are  usually  followed  by  dumb  rabies,  without 
barking  or  fury.  Furious  rabies  can  be  obtained  by 
the  same  methods,  but  with  small  doses  of  virus. 
The  smaller  the  amount  of  the  virus  employed  the 
more  readily  is  the  furious  form  of  the  disease  ob- 
tained, the  period  of  incubation  being  at  the  same  time 
prolonged.  The  injection  of  very  small  doses  maybe 
ineffective  in  the  dog  without  conferring  immunity, 
whilst  inoculation  of  large  quantities  of  virus  may 
give  immunity  without  the  manifestation  of  any 
symptoms  of  rabies. 

Intra-muscular  inoculation  is  followed  by  rabies 
with  more  certaiutv  than  subcutaneous  inoculation. 


302  Manual  of  Veterinary  Microbiology, 

In  the  dog,  iutra-crauial  inoculation  is  always  fol- 
lowed by  furious  rabies;  the  period  of  incubation  for 
the  virus  of  the  streets  is  from  fourteen  to  fifteen 
days,  on  an  average. 

The  inoculation  may  also  be  made  in  the  nerve 
trunks,  a  previous  lesion  of  the  nerve  fibers  increas- 
ing the  chances  of  success;  in  this  method  the  period 
of  incubation  is  not  the  same  in  all  cases,  and  is 
always  longer  than  by  trephining;  the  virus  vege- 
tates in  the  nerve  and  progresses  from  the  periphery 
toward  the  center,  the  disease  being  more  tardy  in 
its  appearance  as  the  course  to  be  traversed  by  the 
virus  is  more  extended.  Inocula'tion  in  the  posterior 
nerve  trunks  is  followed  by  paralytic  rabies;  in  the 
anterior  trunks  by  furious  rabies. 

The  insertion  of  the  virus  into  the  anterior  cham- 
ber of  the  eye  is  invariably  followed  by  rabies,  the 
incubation  in  this  case  being  thirteen  to  sixteen  days 
for  the  natural  virus  of  dogs. 

In  the  rabbit,  intra-cranial  inoculation  enables  us  to 
make  some  important  observations  :  the  incubation 
is  from  fifteen  to  seventeen  days,  and  death  occurs  in 
the  course  of  the  next  four  days.  The  disease  mani- 
fests itself  by  paralytic  phenomena  with  progressive 
course ;  rabies  of  the  rabbit  is,  therefore,  dumb  rabies. 
However,  cases  of  furious  rabies  are  also  observed, 
and  Ferre  has  shown  that  symptoms  of  excitement 
(accelerated  respiration,  etc.)  precede  the  paralytic 
symptoms. 

Passage  of  the  virus  of  natural  rabies  from  the  first 
rabbit  to  a  second,  from  the  second  to  a  third,  and  so 
on,  exalts  the  activity  of  the  rabic  virus.  This  exal- 
tation shows  itself  in  the  shortening  of  the  period  of 


Microbic  Diseases  Individually  Considered.       303 

incubation  which  becomes  abbreviated  to  eight  days 
after  twenty-five  passages  and  to  seven  days  after 
fifty  passages.  The  virus  is  then  acclimated  in  the 
rabbit,  which  dies  regularly  after  seven  days  what- 
ever generation  the  virus  employed  may  belong  to; 
the  virus  of  rabies  thus  exalted  takes  the  name  of 
Jixed  virus.  It  is  exalted  not  only  for  the  rabbit  but 
also  for  the  dog  itself,  which  always  contracts  the  dis- 
ease from  intra-vascular  inoculation  of  this  virus, 
whilst  similar  inoculation  of  natural  virus  is  uncer- 
tain in  its  results. 

In  the  guinea  pig,  which  readily  takes  rabies  by 
intra-cranial  inoculation  of  natural  virus,  virulence  is 
exalted  by  passage  in  series,  until,  after  the  eighth 
inoculation,  it  becomes  fixed.  The  incubation  period 
is  then  five  days.  Rabies  in  the  guinea  pig  often 
shows  a  distinct  period  of  excitement; -the  fixed  virus 
of  the  guinea  pig  is  more  active  for  the  dog  than  the 
natural  virus. 

In  the  ape,  passage  in  series  attenuates  the  viru- 
lence ;  whilst  the  virus  taken  from  the  first  ape  kills 
the  rabbit  in  thirteen  to  sixteen  days,  that  of  the  sec- 
ond allows  an  incubation  in  the  rabbit  of  fourteen  to 
twenty  days,  and  that  of  the  sixth,  thirty  days.  In- 
tra-venous  inoculation  of  the  virus  of  the  sixth  gen- 
eration no  more  produces  the  disease  in  the  dog,  and 
even  intra-cranial  inoculation  is  uncertain.  The  viru- 
lence attenuated  in  the  ape  can  be  restored  to  its 
original  activity  by  a  series  of  passages  through 
rabbits. 

Etiology  and  pathogeny. — Rabies  is  undoubtedly 
caused  bv  a  living  virus.  It  is  transmitted  from  one 
animal   to    another   by    direct   contagion.      Mediate 


304  3Ianaal  of  Veterinary  3Iicrohiology. 

transmission  seems  to  be  of  very  rare  occurrence. 
The  virus  is  preserved  only  for  a  very  short  time  in 
external  media,  a  circumstance  which  diminishes  the 
chances  of  its  transportation;  M.  Galtier,  however, 
has  pointed  out  the  possibility  of  infection  by  the  in- 
tact ocular  mucosa,  and  it  is  quite  conceivable  that 
this  might  actually  occur  in  man  through  tlie  projec- 
tion or  transference  of  a  virulent  liquid  to  the  eye. 
Contamination  by  ingestion  of  the  flesh  coming  from 
a  diseased  animal  appears  to  have  occurred  a  certain 
number  of  times  in  the  dog  (Zundell).  Experimental 
tests  of  this  mode  of  infection  have,  however,  given 
only  negative  results. 

The  disease  is  transmitted  to  the  healthy  individual 
in  nearly  all  cases  by  the  bite  of  a  rabid  animal,  such 
bife  being  equivalent  to  an  inoculation  with  virulent 
saliva.  Bites  of  carnivora  (dog,  cat,  wolf)  are  the  most 
dangerous,  on  account  of  the  severity  of  the  wounds 
which  they  inflict ;  those  of  the  horse  and  deer  are 
less  dangerous;  bovines  have  not  as  yet  been  known 
to  communicate  the  disease.  MM.  Nocard  and  Roux 
have  shown  that  the  virulence  appears  in  the  saliva, 
on  an  average,  twenty-four  hours  before  the  first 
symptoms,  and  that  there  are  cases  in  which  it  ap- 
pears one  or  two  days  earlier.  On  this  account  they 
recommend  that  all  dogs  which  have  bitten  other 
animals  or  human  beings  should  be  kept  under  ob- 
servation for  three  days  at  least  before  certifying  to 
their  condition. 

Bites  which  involve  the  nerves  or  muscles  are 
among  those  which  are  the  most  likely  to  communi- 
cate rabies. 

Besides  bites,  direct  inoculation  may  occur  in  the 


Microbic  Diseases  Individually  Considered.      305 

course  of  an  autopsy.  Inter-placeiitary  transmission 
has  not  been  established ;  cases  of  such  transmission 
which  have  been  brought  forward  have  not  been 
verified. 

The  period  of  incubation  is  very  variable  ;  the  dis- 
ease most  frequently  appears  in  the  course  of  the 
first  two  months  after  the  bite,  but  it  may  appear 
after  a  few  days  as  well  as  after  several  mouths. 
These  diiFcrences  depend  upon  the  more  or  less  easy 
propagation  of  the  virus.  Absorption  takes  place 
chiefly  by  the  nerves ;  in  fact,  inoculation  in  a  nerve 
trunk  induces  rabies  more  rapidly  than  its  insertion 
in  the  connective  tissue  at  a  corresponding  point,  al- 
though less  quickly  than  when  introduced  into  the 
cranial  cavity.  The  virus,  therefore,  seems  to  vege- 
tate in  the  nerve  and  progress  toward  the  cerebro- 
spinal center,  thence  radiating  along  the  nerves. 

After  inoculation  in  the  sciatic  the  primary  rabic 
symptoms  indicate  changes  in  the  lumbar  cord,  the 
cervical  cord  and  the  medula  being  only  attacked  at 
a  later  stage.  In  one  case  in  the  guinea  pig  the  dis- 
ease was  limited  to  paraplegic  symptoms  alone ;  by 
interrupting  the  continuity  of  the  spinal  cord  at  the 
level  of  the  dorso-lumbar  region  the  dorso-cervical 
cord  was  protected  from  the  action  of  the  virus. 
Some  cases  in  man  which  have  been  carefully  ob- 
served support  to  some  extent  this  view  as  to  the 
propagation  of  the  virus  of  rabies:  after  a  bite  on  the 
right  arm  the  nerves  of  this  arm,  inoculated  along 
with  those  of  the  left  arm,  alone  showed  themselves 
virulent.  Incubation  should  therefore  be  shorter  in 
proportion  as  the  length  of  nerve  to  be  traversed  be- 
26 


306  Manual  of  Veterinary  Microbiology. 

fore  amvins:  at  the  center  is  itself  shorter.  How- 
ever,  under  natural  conditions  the  duration  of  this 
latent  period  is  influenced  by  various  factors,  such  as 
the  quantity  of  the  virus,  the  richness  in  nerves,  and 
the  extent  of  the  injury  to  these  nerves. 

The  action  of  the  virus  of  rabies  on  the  nerve  cen- 
ters and  on  the  nerves  is  indirect ;  this  virus  does  not 
act  as  a  chemical  a.s^ent  would,  strychnine,  for  exam- 
ple. The  anatomical  changes,  little  visible  to  the  naked 
eye,  appear  under  the  microscope  as  inflammatory 
lesions  at  difiJerent  stages  of  their  evolution.  These 
lesions  have  their  seat  principally  in  the  nerves  of  the 
bitten  part  and  in  the  corresponding  part  of  the  spinal 
cord.  They  consist  of  congestions  and  capillary 
hemorrhages,  with  infiltration  of  leucocytes ;  other 
lesions  observed  are  limited  foci  of  necrosis,  diverse 
desrenerations  of  the  central  nerve  cells,  transforma- 
tion  of  the  myeline,  hypertrophy  of  the  axis  cylin- 
ders, etc. 

The  rabid  symptoms  are  the  expression  of  the  neu- 
ritis and  myelitis  which  successively  develop.  These, 
changes  manifest  themselves  by  phenomena  of  excite- 
ment or  of  depression  according  as  they  are  more  or 
less  advanced.  Such  phenomena  are  usually  suc- 
cessive in  occurrence,  but  may  appear  separately ; 
hence  the  two  forms,  furious  rabies  and  dumb  or 
paralytic  rabies.  Most  frequently  they  are  combined, 
and  mixed  forms  result,  intermediate  between  the  two 
preceding,  thus  establishing  the  unity  of  the  disease. 
The  symptomatic  tableau  will  naturally  vary  accord- 
ing to  the  part  of  the  cerebro-spinal  axis  first  invaded, 
and  therefore  according  to  the  place  of  inoculation. 

The  experiments  of  Pasteur,  in  which  rabies  was 


Microbic  Diseases  Individually  Considered.       307 

transmitted  by  intra- venous  inoculation,  demonstrate 
the  possibility  ot*  the  absorption  of  the  virus  and  its 
transmission  by  the  circulatory  fluids. 

Attenuation  and  Vaccination. — The  virus  of  rabies  is 
not  absolutely  fixed;  its  passage  through  the  organ- 
ism of  the  rabbit  exalts  its  virulence,  as  we  have  seen 
above,  whilst  its  inoculation  to  the  ape  enfeebles  it.  It 
becomes  acclimated  in  the  ape  after  three  generations 
and  then  requires  an  incubation  of  twenty-three 
days,  the  incubation  for  natural  rabies  being  only 
eleven  days.  The  fixed  virus  of  the  ape  only  rarely 
communicates  the  disease  to  the  dog  by  intra-cranial 
inoculation,  and  intra-venous  inoculation  is  always 
inoffensive ;  this  virus  can  be  ifsed  to  vaccinate  the 
dog. 

Babes  has  shown  that  the  virus  of  rabies  introduced 
into  the  lymph  sac  of  the  frog  becomes  progressively 
attenuated  until,  after  a  certain  time,  it  is  capable  of 
acting  as  a  vaccine  for  the  dog.  The  lymph  of  the 
frog  removed  from  the  body  and  mixed  with  an 
emulsion  of  a  virulent  cord  also  attenuates  the  ac- 
tivity of  the  latter. 

Attenuation  by  desiccation. — A  virulent  rabic  cord 
progressively  loses  its  activity  by  desiccation  in  the 
air.  This  attenuation  manifests  itself  by  retarding 
the  appearance  of  the  disease, — .increasing  the  dura- 
tion of  incubation  ;  thus,  after  two  days'  desiccation 
the  fixed  virus  of  the  rabbit  has  not  changed,  and 
produces  the  disease  in  rabbits  after  seven  days;  after 
three  to  five  days  the  incubation  lasts  for  eight  days; 
after  six  days  it  is  extended  to  fourteen  days ;  after  a 
desiccation  of  more  than  seven  days  the  disease  is  no 
more  communicated  to  the  rabbit.  ^-a-===-._ 

ff  OF  THR  ^ 

I  "UNIVERSITY 


308  Manual  of  Veterinary  Microbiology. 

In  order  to  obtain  a  regular  and  stable  attenuation 
Pasteur  starts  with  the  cord  of  a  rabbit  which  has 
been  rendered  rabid  by  means  of  fixed  virus ;  he  di- 
vides it  into  segments  of  two  centimeters  in  length 
and  these  he  suspends  in  a  wide-mouthed  liter  bot- 
tle containing  pieces  of  caustic  potash ;  this  bottle 
is  placed  in  a  chamber  in  which  the  temperature  is 
maintained  at  20°  C. 

Variations  in  the  temperature  lead  to  modifications 
in  the  attenuation  ;  at  28°  the  virulence  is  destroyed 
in  five  days  ;  at  35°  in  four  hours. 

The  Russian  rabbit,  which  has  a  smaller  cord,  al- 
lows of  a  more  rapid  attenuation. 

The  temperature  and  the  oxygen  of  the  air  are 
instrumental  in  producing  this  loss  of  pathogenic 
activity;  the  attenuation  is  slower  in  carbonic  acid; 
the  loss  of  humidity  seems  to  have  less  influence ; 
ProtopopofF  has,  indeed,  shown  that  this  modication 
occurs  also  in  glycerin-bouillon. 

Authorities  are  far  from  being  unanimous  as  to 
the  theory  of  this  attenuation.  Pasteur  thinks  that 
it  consists  merely  in  an  impoverishment  in  active 
virus  and  not  in  a  diminution  of  activity. 

The  hypothesis  of  a  chemical  vaccine  has  been  dis- 
pelled by  Babes  who  showed  that  the  rabic  sub- 
stance filtered  through  porcelain,  as  ^vell  as  that 
heated  to  100°,  has  no  vaccinal  property.  Gamaleia 
has  demonstrated  that  vaccinal  injections  have  no 
action  on  an  individual  already  afiected  with  the  dis- 
ease, whicii  also  dispels  the  theory  of  a  chemical  vac- 
cine. Virus  attenuated  by  desiccation  regains  the 
activity  of  the  fixed  virus  on  its  second  passage 
through  the  rabbit. 


Microbic  Diseases  Individually  Considered.      809 

Anti-rahic  vaccinations. — It  is  possible  to  confer 
immunity  against  rabies  both  upon  man  and  sus- 
ceptible animals. 

This  immunity  has  been  noted  in  certain  cases  of 
natural  rabies  in  which  recovery  took  place.  It  was 
especially  well  observed  by  Hoegyes  in  cases  of  ex- 
perimental rabies  followed  by  recovery.  This  author 
records  thirteen  cases  of  recovery,  six  being  of  the 
furious  form,  out  of  one  hundred  and  fifty-nine  in- 
oculations to  the  dog.  The  immunity  which  followed 
these  recoveries  was  still  in  force  after  five  years. 

Most  generally,  immunity  is  observed  after  inocu- 
lations which  are  not  followed  by  rabic  symptoms ; 
it  may  be  obtained  in  various  ways.  Pasteur  ob- 
tained it  in  a  dog  by  subcutaneous  inoculation  of 
street  virus  in  large  amount ;  this  immunity,  how- 
ever, is  not  the  rule,  and  in  some  cases  rabies  itself 
appears. 

Hoegyes  obtained  immunity  by  injections  of  fixed 
virus  diluted  in  0*7  per  cent  aqueous  salt  solution. 
He  made  six  inoculations  in  the  dog  with  virus  di- 
luted to  1  to. 5,000,  1  to  2,000,  1  to  500,  1  to  100,  and 
1  to  10.  The  animal  showed  no  sickness  and  con- 
tracted a  solid  immunity  against  bites  and  diverse  ex- 
perimental inoculations. 

Immunity  was  obtained  by  Pasteur  by  inoculating 
the  dog  with  virus  more  or  less  attenuated  in  the 
ape. 

The  same  author  has  conferred  immunity  on  the 
dog  by  subcutaneous  inoculation  of  virus  attenuated 
by  the  method  of  desiccation  above  described.  The 
first  inoculation  is  made  with  the  cord  of  a  rabbit 
desiccated  during  fourteen  days,  that  is,  one  which 


SlO  Manual  of  Veterinary  Microbiology. 

had  lost  virulence  for  the  rabbit  seven  days  before ; 
on  the  following  days  inoculations  were  made  with 
cords  which  had  been  subjected  to  a  less  lengthened 
desiccation  and,  finally,  with  the  virulent  cord.  The 
latter  was  inserted  under  the  skin,  in  the  blood,  or  in 
the  cranial  cavity;  some  of  these  vaccinated  rabbits 
were  subjected  to  bites  of  rabid  dogs ;  these  differ- 
ent virulent  inoculations  produced  no  effects,  and  the 
persistence  of  the  refractory  state  was  verified  several 
years  later. 

Pasteurian  vaccination. — The  period  of  incubation  of 
of  rabies  after  bites  being  quite  lengthy,  Pasteur  con- 
ceived the  idea  of  vaccinating,  during  this  period,  the 
subject  which  had  received  the  bite,  with  tlie  view  of 
preventing  the  invasion  of  the  disease.  Experience 
has  justified  this  illustrious  savant  in  his  belief.  He 
has  succeeded,  by  means  of  a  series  of  dried  cords, 
in  vaccinating  bitten  dogs  and  even  dogs  which  had 
been  inoculated  by  trephining.  It  is  evident  that 
such  preventive  inoculations  should  be  made  as  soon 
as  possible  in  order  that  the  refractory  state  be  estab- 
lished before  the  active  virus  attains  the  nerve  cen- 
ters. The  results  obtained  in  animals  have  served  as 
a  basis  for  the  method  of  preventing  rabies  after  bites 
in  the  human  species,  a  method  which  is  now  applied 
in  several  establishments,  and  the  beneficial  resuhs 
of  which  are  no  longer  contested.  Statistics  show 
that  the  mortality  from  rabies  in  man  has  fallen  from 
16  per  cent  to  0-67  per  cent. 

Prevention  of  rabies  after  bites  in  ruminants. — M. 
Galtier  has  shown  that  the  intra-venous  injection  of 
ruminants  with  the  virus  of  street  rabies  does  not 
communicate  the  disease  but  confers  immunity.     This 


Microbic  Diseases  Individually  Considered.       311 

author  first,  and  later  MM.  ISTocard  and  Roux,  showed 
the  efHcacy  of  this  method  in  the  protection  of 
ruminants  recently  bitten  by  rabid  dogs.  An  emul- 
sion is  made  with  virulent  cord  in  sterilized  water, 
strained  through  a  linen  cloth  and  injected  into  the 
jugular  or  ear  vein.  The  injection,  w^hich  should  be 
of  large  amount,  is  not  attended  with  danger. 

Typhoid  fever  of  the  horse.^ 

Under  the  title  of  the  typhoid  affections  several 
diseases  w^ere  formally  included  which,  clinically,  had 
not  been  sufficiently  difiereutiated.  Our  knowledge 
of  these  diseases  is  now  somewhat  more  extended 
through  the  labors  of  Schlitz,  Perroncito,  Chante- 
messe  and  Delamotte,  Cadeac,  Galtier  and  Violet, 
etc.  Many  points  are  yet  to  be  elucidated,  but  two 
diseases  at  least  have  been  described  which  should 
not  be  included  in  the  group  of  typhoid  affections. 
These  are  pneumonia  or  contagious  pleuro-pneu- 
monia,  and  pneumo-enteritis  of  fodders  which  will 
be  considered  later. 

Equine  typhoid  fever  is  especially  characterized  by 
stupor  and  great  depression  of  the  nervous  and  mus- 
cular systems  of  the  affected  animals;  they  are  weak 
and  unsteady  on  their  feet,  hold  the  head  low,  and 
move  with  a  staggering  gait  as  if  under  the  influence 
of  a  profound  intoxication  or  narcosis ;  the  eyes  are 
weeping,  half-closed,  and  often  inflamed;  the  con- 
junctival mucous  membrane  is  infiltrated,  blood-shot, 

*  [The  term  •' typhoid  fever,"  or  "typhoid  affections"  of  the 
horse  appears  to  include  the  same  diseases  or  complications  of 
one  disease  which  in  England  and  America  are  described  as  In- 
fluenza, Epizootic  cellulitis,  etc. — D.] 


812  Manual  of  Veterinary  Microbiology. 

and  of  a  yellow  tinge  which  may  become  yellowish- 
red  when  conjunctivitis  supervenes. 

The  fever  of  invasion  is  followed  by  diverse  local- 
izations ;  generally  the  digestive  symptoms  predomi- 
nate; the  tongue  is  dry  and  more  or  less  thickly 
coated,  and  symptoms  of  gastro-enteritis  quickly 
appear.  When  the  lungs  become  affected  this  com- 
plication occurs  always  several  days  after  the  begin- 
ning of  the  disease.  The  changes  in  this  organ  also 
differ  absolutely  from  those  which  characterize  in- 
fectious pneumonia.  Typhoid  fever  predisposes  to 
passive  congestions;  hence  the  lung  becomes  cedem- 
atous  rather  than  hepatized  and  tubular  breathing 
over  the  affected  region  is  never  heard,  as  in  the  case 
of  pneumonia.  This  tendency  to  venous  hypersemia 
shows  itself  in  the  limbs  by  oedematous  engorge- 
ments. 

All  attempts  to  transmit  the  typhoid  disease  have 
been  ineffective;  the  horse,  ass,  dog,  and  rabbit  failed 
to  contract  the  disease  by  the  different  methods  of 
inoculation  in  common  use.  Equine  typhoid,  how- 
ever, conducts  itself  like  a  contagious  disease ;  unlike 
contagious  pneumonia  it  is  polymorphic,  showing 
itself  sometimes  as  an  enteritis,  sometimes  as  a  cardi- 
tis, and  sometimes  as  a  disease  of  the  lungs,  etc., 
whilst  in  a  stable  in  which  pneumonia  prevails,  all 
the  affected  horses  show  the  latter  lesion  from  the 
first. 

The  formerly  mooted  question  as  to  the  identity  of 
equine  and  human  typhoid  fever  is  now  settled ; 
Eberth's  bacillus  does  not  occur  in  the  equine  disease 
and  its  inoculation  to  the  horse  remains  without 
effect. 


Microbic  Diseases  Individually  Considered.       313 

Contagious  'pneumonias  of  the  horse.^ 
The  results  obtained  by  different  investigators  re- 
garding contagious  equine  pneumonia  are  far  from 
being  concordant.  Nevertlieless,  it  has  been  well 
established  that  we  must  separate  from  the  typhoid 
afiections  one  or  more  diseases  which  especially  in- 
volve the  lung.  Whilst  in  typhoid  fever  the  pulmo- 
nary localization  is  delayed,  in  infectious  pneumonia 
the  fever  of  invasion  is  of  short  duration  and  the 
disease  localizes  itself  in  the  lung  from  the  first. 
The  early  signs  of  depression  in  pneumonia  are  not 
to  be  compared  with  the  state  of  prostration  of  ani- 
mals affected  with  typhoid  fever,  and  these  symptoms 
subside  when  hepatization  is  accomplished ;  then  the 
animals  recover  their  accustomed  liveliness.  The 
conjunctival  mucous  membrane  has  a  saffron  red  tint, 
the  eye  is  bright  and  well  opened.  A  rusty  discharge 
from  the  nose  appears  during  the  first  stage. 

The  pulmonary  inflammation  may  be  lobar,  occa- 
sionally lobular,  or  it  may  be  complicated  with  pleu- 
risy (pleuro-pneumonia)  ;  other  complications  occa- 
sionally supervene,  afiecting  the  kidney,  synovial 
membranes,  articulations,  the  heart  and  its  serous 
coverings,  the  meninges,  nerve  centers,  gastro-intes- 
tinal  apparatus,  etc. 

Galtier  and  Violet  assert  that  the  intestine  is  often 
affected  along  with  the  lung,  even  as  a  primary  lesion 
(pneumo-enteritig),  and  that  the  disease  also  affects, 

*  [In  English  veterinary  works  referred  to  as  a  complication  of 
influenza.     Ger.  Brustseuche. — D.] 

27 


314  Manual  of  Veterinary  Ilicrohiology. 

secondarily,  the  liver,  spleen  (it  becomes  enlarged 
and  uneven  on  the  surface),  the  bladder,  articula- 
tions, tendinous  sheaths,  muscles,  and  keratogenous 
membrane. 

Schiitz  has  described,  as  the  cause  of  this  disease, 
an  ovoid  microbe,  often  associated  in  pairs  and  which 
possesses  a  capsule  comparable  with  that  of  the 
pneumococcus  of  man.  Perroncito  has  also  observed 
a  capsule,  but  states  that  it  does  not  react  to  staining 
agents  like  that  of  the  pneumococcus;  further,  the 
microbe  studied  by  Perroncito  kills  the  rabbit  and 
the  guinea  pig,  whilst  the  pneumococcus  is  inactive 
for  the  latter.  Chantemesse  and  Delamotte  attribute 
the  disease  to  a  streptococcus.  Galtier  and  Violet 
describe  two  different  microbes  which  gave  two  simi- 
lar diseases :  a  streptococcus  and  a  diplococcus  {strep- 
tococcus et  diplococcus  pneumo-enteritis  eqiii).  Cadeac 
found  in  all  cases  only  one  micrococcus,  often  grouped 
in  pairs,  sometimes  in  chains. 

In  some  investigationsof  our  own,(l)  we  have  found 

(1)  In  several  horses  affected  with  pneumonia  we  have  found  the 
streptococcus  already  described  by  Chantemesse  and  Delamotte 
and  studied  by  Galtier.  The  elements  of  the  chains  are  stained 
by  the  method  of  Gram  and  Weigert;  cultures  in  bouillon  pro- 
duce a  flocculent  precipitate ;  gelatin  is  not  fluidified.  Inoculation 
in  the  rabbit  causes  a  rapid  emaciation  and  a  severe  diarrhoea, 
which  results  in  death  ;  the  latter  is  often  preceded  by  pulmonary 
hemorrhage.  At  the  autopsy  the  blood  is  dark,  little  plastic,  and 
the  serum  deeply  tinged  by  the  coloring  matter  of  the  dissolved 
corpuscles;  the  cavities  of  the  peritoneum,  pleura  and  pericar- 
dium always  contain  an  abnormal  quantity  of  reddish  colored  se- 
rum. The  intestines  are  highly  inflamed ;  Peyer's  patches  are 
injected,  sometimes  studded  with  petechise;  the  liver  is  discol- 
ored and  tumefied;  the  spleen  is  enlarged,  uneven,  dark  and  fri- 
able; the  kidneys  show  congestion  and  extravasation  ;  the  pleura 


Microhic  Diseases  Individually  Considered.      815 

the  streptococcus  of  Chantemesse  and  Delamotte. 
The  microhe  of  Schiitz  and  those  of  Galtier  and  Vio- 
let do  not  take  the  Gram,  whilst  all  the  others  do. 
Most  of  them  are  facultative  anaerobes.  All  are 
pathogenic  for  the  rabhit,  which  contracts  a  rapidly 
fatal  disease :  the  blood  is  decomposed  and  the  color- 
ing matter  of  the  corpuscles,  thus  set  free,  passes 
into  the  serum,  giving  to  the  latter  a  red  tinge,  which  is 
communicated  to  the  liquids  of  the  serous  membranes 
and  to  the  viscera  in  contact  with  these  liquids  ;  the 

sotn&times  contains  a  fibrinous  exudate ;  the  lung  is  much  con- 
gested, this  condition  being  sometimes  complicated  with  intersti- 
tial hemorrhages;  the  blood  often  escapes  into  the  bronchi  un- 
changed ;  once  only  was  hepatization  present  and  that  in  a  rabbit 
whicVi  had  survived  five  days. 

The  guinea  pig  is  a  very  unreliable  reagent  for  the  streptococ- 
cus, whilst  the  dog  is  unaffected  by  it. 

Inoculation  of  5  cc.  of  a  culture  into  the  lung  of  a  glandered 
horse  caused  a  very  intense  febrile  reaction ;  the  temperature  rose 
from  38-5°  to  40-1°  and  remained  at  this  figure  during  several 
days,  whilst  the  animal  showed  complete  inappetence  and  great 
prostration  ;  it  usually  kept  the  recumbent  position  and  had  to  be 
assisted  to  its  feet.  It  was  impossible  to  detect  any  symptoms  of 
pulmonary  disease.  At  the  autopsy,  made  ten  days  later,  nothing 
was  found  at  the  place  of  inoculation,  but  four  pneumonic  centers 
existed  on  the  lower  border  of  the  lobes  of  the  organ.  Three  of 
these  had  the  dimensions  of  a  five  franc  piece,  the  fourth  that  of 
a  child's  hand.  At  these  places  the  lung  was  very  consistent,  of  a 
deep  brown  color,  and  manifestly  hepatized.  Two  other  horses 
received  an  injection  of  a  five  days  old  culture  in  the  lung.  At 
the  autopsy,  made  on  the  following  day  in  one  case,  and  on  the 
third  day  in  the  other,  the  place  of  inoculation  showed  an  inflam- 
matory focus  large  as  a  man's  fist ;  the  hepatized  lung  was  dotted 
with  very  fine  hemorrhagic  points  and  the  visceral  pleura  infil- 
trated with  plastic  serosity  and  notably  thickened.  In  these  le- 
sions the  streptococcus  of  the  cultures  was  found.  None  of  these 
.last  cases  showed  any  febrile  reaction. 


316  Manual  of  Veterinary  Microhiology . 

spleen  is  much  enlarged.  The  diplococcus  pneumo- 
enteritis  equi  has  a  less  pronounced  dissolving  action 
on  the  blood  corpuscles.  Inoculation  to  the  horse 
causes  pneumonia;  this  disease  develops  as  a  conse- 
quence of  injection  into  the  lungs,  trachea,  or  circu- 
lation, but  only  rarely  as  a  result  of  ingestion. 

According  to  Galtier  and  Violet,  the  disease  origi- 
nates when  horses  are  fed  on  forage  of  bad  quality, 
such  as  soiled,  moldy,  or  rusty  hay,  and  imperfectly 
harvested  and  damaged  grain.  These  damaged  foods 
are  the  bearers  of  the  germs  of  the  disease  and  it  is 
by  their  intermediation  that  these  germs  obtain  entry 
to  the  system.  The  dust  rising  from  the  fodder  en- 
ters the  respiratory  passages,  where  the  microbes 
which  it  carries  along  act  directly  upon  the  lung. 
The  disease  has,  in  fact,  been  produced  in  the  horse 
by  inoculation  of  the  products  obtained  by  macera- 
tion of  suspected  foods. 

The  disease  can  then  be  transmitted  from  one  ani- 
mal to  another  by  the  excrements  and  nasal  dis- 
charge; contagion,  according  to  Galtier,  plays  an  ac- 
cessory part;  the  diffusion  of  the  cause  suffices  to 
explain  the  enzootic  and  even  epizootic  character  of 
the  aifection.  Its  transmission,  however,  can  not  be 
doubted. 

Contagious  pleuro-pneumonia  of  cattle. 

Microbe.  —  M.  Arloing  found  that  the  serosity 
which  flows  from  the  surface  of  a  section  through  a 
diseased  lung  is  very  poor  in  microbes  and  that  the 
majority  of  the  culture  bulbs  inoculated  with  a  small 
quantity  of  this  serosity  remain  sterile.  To  obtain 
fertile  cultures  a  large  quantity  of  this  serosity  must 


Microbic  Diseases  Individually  Considered.       317 

be  transferred  to  the  culture  medium,  or  the  inocu- 
lation made  with  the  material  obtained  by  scraping 
the  surface  of  the  section.  By  sowing  the  latter 
product  on  gelatin  M.  Arloing  isolated  four  different 
species,  one  being  a  bacillus  {pneumo-bacillus  lique- 
faciens  bovis)  which  rapidly  fluidifies  gelatin,  and  the 
other  three  micrococci.  Of  the  latter,  one  produces 
white  colonies  resembling  drops  from  a  w^ax  candle, 
the  second  gives  whitish  colonies  which  become 
wrinkled  on  aging,  and  the  third,  colonies  which  take 
an  orange  yellow  tint.  M.  Arloing  attributes  the 
disease  to  the  pneumo-baeillus  liquefaciens  bovis.  The 
four  microbes  inoculated  separately  under  the  skin 
of  a  steer  give  an  inflammatory  tumefaction  which 
disappears  in  five  or  six  days ;  the  largest  tumefaction 
is  caused  by  the  bacillus,  and  if  several  successive 
generations  are  inoculated  it  ultimately  happens  that 
the  bacillus  alone  produces  a  local  reaction.  More- 
over, the  bacillus  alone  is  constantly  present  in  dis- 
eased lungs.  M.  Arloing  noticed  that  the  isolated 
effects  of  the  microbes  which  he  had  cultivated  re- 
sembled only  in  a  remote  way  those  produced  by 
fresh  serosity,  but  he  observed,  also,  that  this  last 
becomes  more  active  in  passing  through  the  cellular 
tissue  of  healthy  cattle.  By  taking  the  microbes 
from  this  reinforced  serosity  he  obtained  more  viru- 
lent cultures  of  the  pneumo-baeillus ;  4  cc.  of  cul- 
ture injected  into  the  lung  of  one  steer  and  20  cc. 
injected  into  the  veins  of  another  produced  the  speci- 
fic lesions  of  pleuro-pneumonia.  This  author  isolated 
from  cultures  a  soluble  substances  which  possesses 
remarkable  phlogogenic  properties,  and  which,  of 
itself  alone,  reproduces  the  characteristic  inflammatory 


318  Manual  of  Veterinary  llicrobiology. 

engorgements  of  the  hypodermic  inoculation  of  active 
virus.  He  attributes  to  this  substance  the  inflamma- 
tions which  sometimes  occur,  in  the  course  of  the 
natural  disease,  in  points  remote  from  the  thorax. 

Whatever  opinion  may  be  held  regarding  these  in- 
vestigationS;,  the  virulent  agent  of  pleuro-pneumonia 
exists  in  the  serosity  which  flows  in  abundance  when 
a  diseased  lung  is  incised.  Inoculation  of  this  liquid 
produces  the  following  effects : 

In  the  subcutaneous  cellular  tissue  a  more  or  less  in- 
tense inflammatory  engorgement  results ;  in  regions  in 
which  the  connective  tissue  is  loose  and  abundant 
this  reaction  often  assumes  a  severe,  progressive  and 
occasionally  gangrenous .  character,  and  leads  to 
death  ;  the  general  effects  of  the  virus  are  indicated 
by  a  febrile  reaction  of  greater  or  less  intensity. 
Pleuro-pneumonia  is  almost  never  observed  as  a  con- 
sequence of  subcutaneous  insertions.  But  the  latter 
confers  immunity  against  later  inoculations. 

The  injection  of  the  virus  into  the  veins  gives  no 
more  characteristic  pulmonary  lesions ;  it  confers 
immunity  without  any  local  manifestation,  unless 
some  of  the  virus  should  fall  on  the  perivascular 
cellular  tissue,  in  which  case  a  dangerous  tumor  re- 
sults. M.  Thiernesse,  however,  observed  pleuro-pneu- 
monia after  an  injection  of  35  grams  in  the  jugular. 

Vacciiiaiion. — In  1852  "VYillems  recommended  pre- 
ventive inoculation  against  this  disease;  his  method 
was  put  in  practice  in  different  places  and  the  pre- 
ventive action  of  Willemsian  inoculation  placed  be- 
yond doubt. 

The  inoculation  may  be  performed  in  three  princi- 
pal ways :  by  dermic,  hypodermic,  and  intravenous 


Microbic  Diseases  Individually  Considered.       319 

insertion.  Dermic  insertion  gives  uncertain  results, 
the  virulent  Kiatter  requiring  to  be  brought  into  the 
cellular  tissue  in  order  to  act  efficaciously.  On  the 
other  hand,  hypodermic  injection  supplies  the  best 
conditions  for  the  evolution  of  the  virus.  For  the 
reception  of  the  pulmonary  serosity  the  cellular  tis- 
sue of  the  tail  should  be  selected  in  preference  to  all 
other  regions;  as  has  already  been  said  the  conse- 
quences of  inoculation  are  often  very  severe  in  regions 
where  the  connective  tissue  is  loose  and  abundant. 
In  the  tissue  of  the  tail,  one  or  two  drops  of  the 
serosity  are  sufficient.  It  is  well  to  make  a  second 
vaccination  a  few  weeks  later ;  this  may  be  made  in 
an  interdicted  region  although  this  procedure  can  not 
be  recommended,  especially  when  the  reaction  to  the 
first  inoculation  has  been  insufficient. 

With  the  view  of  obviating  the  accidents  which 
occasionally  follow  the  caudal  inoculation  some  ex- 
perimenters, including  Professor-Director  Degive, 
have  had  recourse  to  intravenous  injection ;  this 
method  procures  a  solid  immunity,  but  requires  special 
care  in  order  to  avoid  accidental  contact  of  the  virus 
with  the  cellular  tissue  which  surrounds  the  vein,  an 
accident  which  may  result  in  a  serious,  perhaps  fatal, 
eno:orgement.  Larger  doses  may  be  introduced  into 
the  veins  than  into  the  cellular  tissue. 

For  the  practice  of  Willemsian  inoculation  it  is 
essential  that  fresh  virus  be  employed.  This  is  ob- 
tained by  making  a  clean  incision  of  a  diseased  lung 
with  an  aseptic  knife  and  collecting  the  serosity 
which  flows  spontaneously  from  regions  in  which  the 
inflammation  is  most  recent.     As  such  a  lung  is  not  al- 


320  Manual  of  Veterinary  Microbiology. 

ways  at  hand  efforts  have  been  made  to  preserve  the 
virus. 

M.  Laquerriere  showed  that  in  a  frozen  lung  the 
virus  remains  intact  for  one  year,  at  least. 

M.  Nocard  has  quite  recently  recommended  the 
preservation  of  the  virus  by  the  addition  of  half  a 
volume  of  a  five  per  cent  solution  of  carbolic  acid 
and  half  a  volume  of  pure  neutral  glycerin.  This 
mixture  retains  its  virulence  for  months. 

For  the  purpose  of  procuring  pure  virus  some  have 
advised  its  cultivation  by  direct  inoculation  in  the 
cellular  tissue  of  the  calf  and  collecting  the  serosity 
of  the  inflammatory  engorgement. 

Others  again  have  sought  for  a  means  of  mitigating 
the  eflects  of  the  natural  virus  in  order  to  diminish 
the  accidents  which  result  from  its  use;  Pasteur  has 
shown  that  it  is  preserved  for  six  weeks  in  sealed 
tubes,  but,  at  the  same  time,  becomes  so  attenuated 
that  it  can  be  inoculated  in  an  interdicted  region 
without  exciting  fatal  lesions.  It  has  also  been  pro- 
posed to  dilute  the  virus  in  water.  Dilutions  of  1  to 
50,  1  to  100,  and  1  to  500  have  yet  sufficient  activity 
to  produce  considerable  inflammatory  reactions  and, 
therefore,  to  confer  immunity. 

Septic  pleuro-pneumonia  of  calves. 
This  disease  occurs  in  an  enzootic  form  on  certain 
farms,  attacking  and  quickly  killing  calves  while  still 
quite  young.  The  lesions  by  which  it  is  characterized 
have  some  analogy  with  those  of  contagious  pleuro- 
pneumonia of  larger  cattle,  but  the  thickening  of  the 
connective  tissue  septa  is  less  marked  and  the  flow 
of  serosity  less  abundant,  whilst  the  individual  pul- 


Microbic  Diseases  Individually  Considered.       321 

monary  lobules  have  not  the  uuiform  color  seen  in 
the  latter  disease.  We  have  observed  that  the  pul- 
monary lesions  begin,  as  in  pleuro-pneumouia,  in  the 
interlobular  connective  tissue  and,  in  the  peripheral 
lobules,  progress  toward  the  center.  Peels  has 
noted,  in  calves  affected  with  this  disease,  the  fre- 
quency of  sero-fibrinous  exudates  and  pleuritic  ad- 
hesions, lesions  which  have  also  been  recorded  by 
M.  Vanden  Maeghdenbergh.  He  also  mentions  the 
occasional  occurrence  of  inflammations  of  the  peri- 
cardium, liver,  kidneys,  stomach  and  intestine. 

Microscopical  examination  shows,  in  the  lung  and 
in  the  muco-pus  of  the  bronchi,  the  presence  of  ovoid 
microbes  with  rounded  ends,  measuring  from  Ip.  to 
1-5/i  in  length  by  0-5/i  in  thickness,  easily  stained  by 
the  aniline  colors,  but  not  stained  by  the  Gram  or 
"Weigert  methods.  When  stained  with  a  very  dilute 
aqueous  solution  of  gentian  violet  they  fix  the  color 
at  their  extremities,  whilst  the  center  remains  clear. 
They  are  motile,  vegetate  rapidly  in  bouillon  and  on 
Bolid  media,  and  are  pathogenic  for  various  species 
of  animals. 

The  rabbit  dies  in  twenty-four  to  forty-eight 
hours  after  subcutaneous  inoculation  or  ingestion  of 
cultures  or  virulent  products.  In  the  same  animal 
intra-pulmonary  inoculation  of  a  drop  of  culture  pro- 
duces a  pneumonia.  Death  is  a  little  later  in  the 
guinea  pig  than  in  the  rabbit. 

■^  Two  calves,  aged  thirteen  days  and  eight  weeks, 
and  a  one-year-old  heifer,  were  inoculated  by  Poels, 
the  first  in  the  right  pleura,  the  second  in  the  trachea, 
and  the  third  in  the  lung.  They  died  after  20,  54, 
and   66   hours,  respectively,  with  lesions   of   septic 


322  Manual  of  Veterinary  Microbiology. 

pleuro-pneumonia.  A  pig  also  took  the  disease  bj 
pulmonary  injection;  the  sheep  and  the  dog  are  re- 
fractory (Poels).  The  microbe  is  described  as  a  facul- 
tative parasite  capable  of  living  in  the  soil,  which 
fact,  according  to  Poels,  explains  the  persistence  of 
the  disease  on  an  infected  farm.  M.  Galtier  thinks 
that  the  latter  ought  to  be  attributed  to  the  mothers 
(see  page  325).  However  that  may  be,  its  transmis- 
sion from  calf  to  calf  must  be  admitted  ;  the  virulent 
germs  are  spread  around  with  the  expectorations  and 
perhaps  with  the  excrements  (Poels  claims  to  have 
found  the  germs  in  all  the  organs).  These  microbes, 
and  especially  those  of  the  nasal  discharge,  con- 
taminate the  vessels  in  which  milk  is  fed  to  the  dis- 
eased, and  the  same  vessels  are  then  used  for  other 
animals.* 

The  microbe  of  this  pleuro-pneumonia  of  calves 
belongs  to  the  great  class  of  ovoid  bacteria  showing 

*  [In  the  diarrhoea  or  dysentery  of  young  calves  known  as 
"white  scours"  [Ger.  Kalberruhr)  Jensen  (1892)  discovered  in 
the  blood,  spleen,  liver,  kidneys  and  lungs,  as  well  as  in  the  mu- 
cous membrane  of  the  intestine,  oval  bacteria,  isolated  or  asso- 
ciated in  pairs  or  short  chains,  staining  at  the  extremities  only, 
and  easily  cultivated  in  the  various  artificial  media.  Bouillon 
cultures  fed  to  young  calves  in  doses  of  5  cc.  produced  the  charac- 
teristic diarrhoea  and  death  in  from  one  to  two  days.  From  the 
contents  of  the  intestine  of  healthy  calves  he  isolated  apparently 
the  same  germ  but  found  it  destitute  of  pathogenic  properties. 
Jensen  came  to  the  conclusion  that  the  microbe  is  a  facultative 
parasite,  a  usually  harmless  inhabitant  of  the  intestinal  canal  but 
one  which  under  certain  abnormal  conditions  of  the  intestine 
(perhaps  attributable  to  the  diet)  acquires  pathogenic  properties 
which  become  increased  by  subsequent  passage  from  calf  to 
calf.— D.] 


Microbic  Diseases  Indkidually  Considered.       323 

a  clear  central  space,  which  are  met  with  in  a  series  of 
diseases.  Hueppe  groups  these  affections  under  the 
name  of  hemorrhagic  septiccemias  and  attributes  them 
all  to  the  same  germ.  These  diseases  are  :  Koch's  rab- 
bit septicismia,  fowl  cholera,  duck  cholera,  parrot  dis- 
ease, infectious  pneumonia  of  the  pig,  pneumo-enteritis 
of  the  pig,  pneumo-enteritis  of  sheep,  epizootic  of  wild 
game  (Wildseuche),  epizootic  of  ferrets,  disease  (bar- 
bone)  of  buffaloes,  etc.  It  would  be  superfluous  to  in- 
sist on  the  non-identity  of  the  germs  of  these  different 
affections,but  their  close  relationship  can  not  be  denied. 
The  morphological  characters  of  the  germs  are  almost 
identical;  all  take  the  stain  only  at  their  extremities, 
leaving  a  clear  space  in  the  middle;  they  do  not  stain 
by  the  Gram  method,  do  not  fluidify  gelatin,  and  are 
pathogenic  for  rabbits.  It  is  probable  that  several  of 
the  diseases  mentioned  above  are  due  to  one  and  the 
same  microbe  (fowl  cholera  and  rabbit  septicemia, 
for  example)  and  that  all  these  micro-organisms  rep- 
resent varieties  of  one  fundamental  species.* 

*  [Billings  found  in  specimens  of  the  blood  and  organs  of  cattle 
which  had  died  from  the  so-called  "corn-stalk"  or  "corn-fodder 
disease  "  of  the  "Western  States  an  organism  presenting  great  mor- 
phological resemblance  to  the,  germ  of  "swine  plague"  (hog 
cholera)  but  showing  slight  differences  in  its  growth  on  the  vari- 
ous culture  media.  It  belongs  to  the  group  of  ovoid,  bi-polar  stain- 
ing organisms  and,  according  to  this  author,  is  the  cause  of  the 
disease  above  named.  The  germ  was  found  to  be  pathogenic  for 
mice,  rabbits  and  guinea  pigs ;  subcutaneous  inoculation  of  a  steer 
gave  rise  to  fever,  pneumonia  and  pleurisy,  and  great  emaciation, 
terminating  in  recovery.  From  the  original  communications  on 
this  subject  we  learn  that  the  germ  is  identical  with  a  bacterium 
described  by  Burril  as  the  cause  of  a  disease  of  corn  (maize) 
{Ills.  Univ.  Exper.  Sta.  Bui.  6),  and  the  cattle  become  infected  by 
feeding  on  the  leaves  of  this  diseased  corn.    Horses  are  also  said 


324  Manual  of  Veterinary  Microbiology. 

Epizootic  abortion. 

Epizootic  abortion  is  a  contagious  disease  most  fre- 
quently seen  in  the  cow  but  also  noticed  in  the  ewe, 
she-goat,  and  even  in  the  mare.  The  abortion  occurs 
at  all  periods  of  gestation  after  the  third  month ;  in 
the  same  animal  it  occurs  at  a  later  stage  in  each  suc- 
ceeding year  and  at  length  allows  the  foetus  to  be 
carried  till  term,  if,  indeed,  the  cow,  after  a  first 
abortion,  has  not  become  sterile.  The  calf  is  most 
frequently  still-born ;  iii  some  cases  it  is  born  alive  but 
its  health  is  precarious;  shortly  after  birth  it  emits  a 
peculiar  lowing;  after  the  third  day  it  is  attacked 
with  diarrhoea  and  death  quickly  follows. 

According  to  ISTocard  the  disease  takes  its  origin  in 
diverse  germs  met  with  in  the  uterus  of  the  animals 
which  abort,  germs  which  are  never  found  in  healthy 

to  die  from  the  same  disease  {Neh.  Agric.  Exper.  Station,  Bulletins  7, 
8,  9,  10). 

Nocard  studied  an  "infectious  broncho-pneumonia"  which  was 
observed  in  a  number  of  recently  imported  American  cattle  (from 
Virginia,  Indiana  and  Illinois).  The  lesions  in  the  lung  some- 
what resembled  those  of  contagious  pleuro-pneumonia.  The 
muco-pus  of  the  bronchi,  the  hepatized  lung  tissue,  and  the 
serosity  contained  a  short,  ovoid,  motile  bacterium,  apparently  in 
pure  culture.  It  measured  barely  Ifi  in  length  by  0"3,u  to  0'4,u  in 
thickness,  stained  with  aqueous  solutions  of  fuchsin  and  methy- 
lene blue,  leaving  a  clear  unstained  central  space  ;  not  stained  by 
the  methods  of  Gram  or  Weigert.  The  germ  was  found  to  be 
pathogenic  for  the  mouse,  rabbit,  guinea  pig  and  pigeon,  which 
die  from  subcutaneous  inoculation ;  inoculated  in  the  lung  of 
calves  and  sheep  it  occasions  a  fatally-ending  exudative  broncho- 
pneumonia. Nocard  believes  this  disease  to  be  identical  with 
the  "  corn  fodder  disease  "  of  Billings.  {Recueil  de  Med.  Vet.  Aug., 
1891.— D.] 


Microhk  Diseases  Individually  Considered.       325 

animals.  These  germs,  among  which  is  often  found 
a  micrococcus,  isolated  or  in  chains,  are  also  present 
in  the  amniotic  fluid,  in  the  digestive  canal  of  the 
aborted  calves,  as  well  as  in  the  substance  of  the 
medulla  oblongata  of  those  individuals  whicb  during 
life  gave  utterance  to  the  peculiar  lowing  sound  just 
referred  to.  N"ocard  thinks  that  these  germs  give  rise 
to  a  disease  of  the  foetus  and  its  envelopes,  the  mother 
remaining  healthy.  He  explains  the  repeated  abortion 
by  the  persistence  of  these  germs  in  the  womb,  and 
the  sterility  by  the  acid  reaction  which  they  produce 
in  the  uterine  secretions. 

The  invasion  of  a  stable  by  this  disease  generally 
coincides  with  the  introduction  of  a  pregnant  infected 
cow ;  abortion  then  occurs  annually  in  a  certain  num- 
ber of  animals  in  this  stable.  The  lengthy  period  of 
incubation  of  the  disease  implies  an  early  infection. 

Galtier  thinks  that  the  disease  is  due  to  a  general 
infection  of  the  mother,  which  communicates  the  dis- 
ease to  the  foetus.  Calves  which  are  not  prematurely 
expelled  will  still  harbor  the  germs,  and  these  germs 
produce  the  pneumo-enteritis  which  occasions  such 
ravages  in  these  animals. 

In  short,  epizootic  abortion  appears  to  depend  on 
multiple  causes  which  are  yet  to  be  discovered,  but 
in  all  cases  the  method  of  treatment  laid  down  by 
ISTocard  is  to  be  recommended. (1) 

(1)  The  prophylactic  measures  recommended  are  as  follows : 

1.  Each  week  the  floor  of  the  stable  should  be  scraped,  thor- 
oughly cleansed,  and  sprinkled  with  a  solution  of  sulphate  of 
copper:  40  grams  to  the  litre. 

2.  Each  week  from  the  date  of  conception  the  vagina  of  the 


326  Manual  of  Veterinary  3Iicrobiology. 


Contagious  mammitis  of  milch  cows. 

MM.  ISTocard  and  Mollereau  have  seen  and  de- 
scribed a  special  form  of  mammitis  occurring  in 
milch  cows  and  readily  passing  from  one  animal  to 
another.  It  appears  in  the  form  of  indurated  lumps 
which  commence  at  the  base  of  the  teat,  gradually  in- 
crease in  size,  and  may  sooner  or  later  invade  the 
whole  organ.  The  milk  is  diminished  in  quantity, 
becomes  acid  in  reaction,  and  soon  coagulates — often 
as  soon  as  it  is  drawn  from  the  udder ;  it  is  often 
mixed  with  pus,  and  grumous;  sometimes  it  exhales 
an  offensive  odor.  These  characters  it  communicates 
to  good  milk  with  w^hich  it  may  be  mixed. 

Microbe. — This  is  a  rounded  or  ovoid  micrococcus; 
it  measures  l-2bfjt  in  length  by  l/jt.  in  thickness  and 
forms  long  straight  or  sinuous  chains.  It  frequently 
appears  bi-lobed,  in  way  of  division.  It  is  aero- 
pregnant  cows  should  be  thoroughly  injected  by  means  of  a  large 
syringe,  with  the  following  tepid  solution : 

Distilled  water,  ...  20  liters. 

36  percent  alcohol)  -.  i^^ 

^,  *      ,  Vaa    .  .  .100  grams. 

Glycerin,  ) 

Bichloride  of  mercury,  .  .  10  grams. 

3.  Each  week,  at  the  time  of  grooming,  the  vulva,  anus,  and 
lower  surface  of  the  tail  of  all  the  pregnant  cows  should  be  care- 
fully washed  with  a  sponge  saturated  with  the  same  tepid  solu- 
tion. 

4.  If  a  cow  should  abort  it  will  be  necessary  to  remove  the 
placenta  by  hand,  to  destroy  the  foetus  and  after-birth  by  fire  or 
boiling  water,  and  to  irrigate  the  uterus  by  means  of  a  long  tube 
introduced  to  the  bottom  of  the  cavity,  with  eight  or  ten  liters  of 
the  tepid  solution  indicated  above  but  containing  only  half  the 
proportion  of  sublimate. 


Microbic  Diseases  Individually  Considered.      327 

anaerobic.  These  characteristic  chains  are  found  in 
the  milk  and  in  the  wall  of  the  excretory  ducts. 

Action  of  physical  and  chemical  agents. — The  growth 
of  the  microbe  in  cultures  is  checked  by  a  trace  of 
boric  acid;  MM.  Nocard  and  Mollereau,  taking  ad- 
vantage of  this  peculiarity,  injected  on  several  occa- 
sions at  intervals  of  eight  days  100  grams  of  a  tepid 
four  per  cent  aqueous  solution  of  boric  acid  into  the 
teats  of  the  affected  udders,  the  injection  naturall}' 
being  made  immediately  after  milking.  The  parjj,site 
is  also  destroyed  by  a  three  per  cent  solution  of  car- 
bolic acid  ;  the  authors  recommend  this  solution  for 
washing  the  hands  of  those  who  undertake  the  milk- 
ing. By  these  measures  they  succeeded  in  arresting 
the  extension  of  the  disease. 

Cultures. — Alkaline  bouillon  with  the  addition  of 
sugar  or  glycerin  forms  a  medium  well  suited  for  its 
growth ;  at  35°  it  forms  a  mass  of  very  long  chains 
which  sometimes  become  agglomerated  in  silky  flakes 
which  after  several  days  are  deposited ;  the  reaction 
becomes  acid  in  twenty-four  to  forty-eight  hours;  if 
chalk  be  added  to  the  bouillon  so  as  to  neutralize  the 
acid  as  it  is  produced,  the  culture  is  more  vigorous 
and  retains  its  vitality  longer.  Crystals  of  lactate  of 
lime  are  often  found  at  the  bottom  of  the  bulb.  The 
growth  of  this  microbe,  therefore,  gives  rise  to  the 
lactic  fermentation  ;  it  can  not,  however,  be  identi- 
fied with  the  lactic  bacillus.  Cultures  almost  in- 
variably die  after  a  few  weeks.  The  microbe  grows 
also  on  the  different  solid  media. 

Experimental  inoculations. — Inoculation  of  pure  cult- 
ures into  the  teat  reproduced  the  disease  in  the  cow 
and  the  goat;  from  the  first  day  the  inoculated  udders 


328  Manual  of  Veterinary  Microbiology. 

supplied  a  milk  very  rich  in  streptococci;  that  from 
the  cow  quickly  showed  an  acid  reaction  and  became 
clotted;  the  udder  finally  became  inflamed.  Inocu- 
lation in  the  mamma  of  a  nursing  bitch  remained 
without  etiect;  the  dog,  cat,  rabbit,  and  guinea  pig 
were  also  unaffected  by  intra-venous  and  intra  peri- 
toneal inoculations. 

Etiology. — The  disease  is  communicated  through 
the  intermediation  of  those  who  have  charge  of  the 
milking  of  the  cows,  their  hands  being  soiled  with 
the  diseased  milk.  When  the  latter  is  mixed  with 
good  milk  this  also  takes  the  same  characters.  Con- 
tagion to  the  cows  must,  therefore,  be  prevented  by 
disinfection  of  the  hands,  and  contagion  to  the  nor- 
mal milk  by  keeping  the  milk  from  the  diseased  cows 
in  separate  vessels.  Such  milk  is,  moreover,  unfit  for 
human  consumption. 

Besides  this  disease,  remarkable  on  account  of  its 
extreme  contagiousness,  the  udder  of  the  cow  is  sub- 
ject to  various  microbic  lesions.  M.  Lucet  especially 
called  attention  to  infectious  forms  of  mammitis  due 
to  an  external  cause;  in  a  series  of  cases  of  acute 
mammitis  he  found  one  or  several  germs;  these  were 
sometimes  micrococci,  sometimes  bacilli,  and  some- 
times both  together.  Penetration  of  the  germs  most 
frequently  occurs  through  solutions  of  continuity  of 
the  integument  of  the  udder.  The  microbe  being 
different  in  different  cases,  we  can  readily  under- 
stand that  the  severity  of  the  disease  will  be  very 
variable. 

Among  the  number  of  infectious  forms  of  mam- 
mitis with  internal  cause  tubercular  mammitis  should 
be  especially  mentioned. 


Microbie  Diseases  Individually  Considered.      329 

Gangrenous  mammitis  of  milch  ewes. 
This  disease,  also  called  mal  de  pis,  araignee,  quickly 
kills  ewes  which  are  attacked  by  it;  it  is  due,  accord- 
ing to  the  researches  of  M.  J^ocard,  to  a  very  fine  mi- 
crococcus, measuring  0-2//  in  diameter,  and  associated 
in  groups  of  four  or  more,  never  in  chains.  It  is 
stained  by  the  method  of  Gram,  is  aero-anaerobic, 
and  communicates  to  bouillon  and  to  milk  an  acid 
reaction,  coagulating  the  latter  in  twenty-four  hours. 
Cultures  retain  their  virulence  only  when  renewed 
every  day.  When  a  culture  is  inoculated  into  the 
teat  of  a  ewe  it  produces  a  rapidly  fatal  mammitis. 
The  goat  is  refractory.  The  rabbit  contracts  an  ab- 
scess from  which  it  quickly  recovers.  The  dog,  cat, 
and  guinea  pig  show  only  a  local  oedema. 

Diseases  of  milk. 

Milk  just  withdrawn  from  the  udder  is  free  from 
germs,  but  after  its  extraction  it  may  quickly  become 
infected  and  undergo  a  series  of  deteriorating  changes. 
The  most  important  of  these  deteriorations  will  here 
be  briefly  described. 

Curdled  milk. — The  curdling  of  milk  results  from 
the  lactic  fermentation  of  milk  sugar,  the  acid  pro- 
duced then  bringing  about  the  coagulation  of  the 
casein. 

The  usual  cause  of  this  fermentation  is  the  bacte- 
rium lactis.  This  is  a  short,  non-motile  rod,  measur- 
ing in  length  1/i  to  8//  by  0*6//  in  thickness,  most  fre- 
quently isolated  but  occasionally  arranged  in  series, 
and  capable  of  spore  formation. 
28 


330  Manual  of  Veterinary  Microbiology. 

Other  germs  give  rise  to  the  same  deterioration  of 
milk,  among  these  being  the  cocci  of  suppuration, 
erysipelas,  contagious  mammitis  of  the  cow,  etc. 
The  infection  occasionally  originates  in  the  udder 
(mammitis),  more  frequently,  however,  after  the  milk 
is  withdrawn.  The  infection  is  facilitated  by  lack  of 
cleanliness  in  the  stables,  dairy  utensils,  etc. 

The  diseased  milk  coagulates  more  or  less  quickly 
according  to  circumstances ;  the  process  is  hastened 
by  heat.  The  cream  separates  imperfectly  from  such 
milk  and  the  agglomeration  of  the  butter  globules  is 
difficult. 

Putrid  milk. — Milk,  like  all  organic  liquids,  readily 
putrefies.  Various  ]3utrefactive  germs  are  concerned 
in  this  process,  but  those  which  are  most  constant 
are  the  bacterium  termo  and  lineola. 

The  former  is  represented  by  short  motile  rods, 
measuring  l-4^«  by  0-7//.  The  second  species  consists 
of  large  cylindrical,  motile  rods,  measuring  3/i  to  5// 
by  Vbfx. 

Infection  results  from  lack  of  cleanliness ;  the  in- 
fected milk  quickly  putrefies,  with  the  production  of 
putrid  gas  in  its  substance.  At  the  same  time  the 
cream  takes  a  yellow  color  and  a  bitter  or  rancid 
taste,  and  butter  can  no  longer  be  obtained  from  it; 
it  then  gradually  disappears. 

Viscous  milk. — In  this  form  of  deterioration,  which 
is  observed  one  or  two  days  after  milking,  the  milk 
is  not  readily  coagulable  and  the  cream  separates  im- 
perfectly;  butter  is  obtained  with  diflficulty  and  has  a 
disagreeable  taste. 

The  disease  is  due  to  rounded  elements  Ip.  in  di- 
ameter, isolated  or  associated  in  the  form   of  chains, 


I  TJNIVERSIT" 


Mlcrohic  Diseases  Individually  Considered.       331 

and  transforming  the  lactose  into  a  mucilaginous 
substance  which  gives  to  the  milk  its  peculiar  con- 
sistence. 

Blue  milk. — It  sometimes  happens  that  m.ilk,  from 
twenty  to  thirty-six  hours  old,  shows  on  its  surface 
small  light-blue  patches  which,  later,  take  an  indigo- 
blue  shade.  These  patches  increase  in  area  as  w^ell 
as  in  depth  although  never  exceeding  the  thickness 
of  the  cream.  Such  milk  is  highly  subject  to  change; 
it  quickly  becomes  acid,  coagulates  and  then  putre- 
fies. 

The  causative  agent  of  blue  milk  is  the  bacillus 
cyanogenus.  This  is  a  motile  rod,  2/j.  to  4/x  long  by 
0-5/i  thick,  commonly  isolated  but  sometimes  united 
in  a  zooglcea.  The  spore  which  it  produces  is  a 
little  larger  than  the  bacillus  giving  to  the  latter  a 
club  or  spindle-shaped  appearance.  In  certain  artifi- 
cial media  it  assumes  very  diverse  involution  forms — 
balloon  and  ribbon  shapes,  etc.  Grown  on  the  gela- 
tin plate  it  forms,  after  tw^o  days,  small  whitish  spots 
which  soon  extend  over  the  whole  surface  giving  it 
a  bluish  color.  Stab  cultures  in  gelatin  show  whitish 
colonies  on  the  surface  and  steel  blue  in  the  depth. 

When  inoculated  to  milk  it  increases  the  alkalinity 
of  the  latter  and  the  layer  of  cream  becomes  slate 
colored,  this  tint  turning  to  blue  on  the  addition  of 
acid.'  If  the  milk  has  not  been  sterilized  the  lactic 
acid  fermentation  which  goes  on  at  the  same  time 
supplies  the  acid  by  which  the  blue  color  is  pro- 
duced. 

The  germ  multiplies  in  albuminous  solutions  con- 
taining lactate  of  ammonia,  without  producing  the 
coloring  principle. 


332  Manual  of  Veterinary  Microbiology. 

This  coloring  matter  is  most  abundantly  produced 
at  about  20°,  in  less  amount  at  25°,  and  not  at  all  at 
37°.  The  pigment  is  a  soluble  substance  which  gives 
a  red  reaction  with  potash,  violet  with  ammonia. 
Inoculation  of  this  germ  to  animals  produces  no  re- 
sult. 

The  infection  of  milk  takes  place  after  its  with- 
drawal from  the  udder  and  is  contingent  upon  a  pre- 
vious infection  of  the  dairy  or  of  the  stable. 

Cheese  made  from  infected  milk  may  also  show 
this  blue  color,  but  the  latter  changes  more  or  less 
to  green  in  consequence  of  the  yellow  color  which 
cheese  assumes  in  aging. 

Red  milk. — Two  species  of  germs  are  capable  of 
imparting  a  red  color  to  milk.  One,  the  micrococcus 
j^rodigiosus,  is  elliptical,  motile,  and  forms  on  potato 
an  abundant  slimy  growth  of  blood-red  color.  The 
infected  milk  shows  on  the  surface  a  pellicle  of  a 
more  or  less  deep  red  color,  the  deeper  layers  remain- 
ing unaltered.  Another,  the  bacterium  lactis  erythro- 
gbies,  is  a  very  short  non-motile  rod.  In  milk  it 
slowly  precipitates  the  casein  and  the  whole  mass  as- 
sumes a  blood-red  color. 

Red  milk  is  of  much  rarer  occurrence  than  blue 
milk. 

Yellow  milk. — This  deterioration  occurs  especially 
on  boiled  milk ;  golden  yellow  patches  appear  on  the 
milk  which,  at  the  same  time,  coagulates  and  becomes 
alkaline.  The  change  is  produced  by  the  growth  of 
the  bacillus  synxanthus,  a  slender,  very  mobile  rod. 

Bacterial  hcemoglobinuria  of  cattle. 
This  acute  febrile  disease  prevails  in  an  endemic 


Mlcrohic  Diseases  Individually  Considered.      333 

form  in  certain  marshy  regions  of  Roumania,  where 
it  causes  the  loss  of  large  numbers  of  oxen.  Cows 
are  less  susceptible  while  calves  seem  to  be  refractory. 
It  is  characterized  by  the  presence  of  albumen  and 
haemoglobin  in  the  urine ;  the  latter  is  red  colored 
but  does  not  contain  blood  corpuscles.  The  autopsy 
reveals  the  presence  of  interstitial  extravasations  and 
ulcers  of  the  fourth  stomach  and  duodenum.  The 
tissue  surrounding  the  kidneys  is  infiltrated  with 
blood  and  serosity,  the  kidneys  are  friable  and  dark 
red  in  color  and  their  pelvic  mucous  membrane 
ecchymosed;  the  bladder  is  filled  with  red  colored 
urine.  The  liver  is  tumefied  and  discolored,  the 
spleen  enlarged  and  darkened  and  the  pulp  difiluent. 

Babes  has  discovered  in  this  disease  a  rounded  mi- 
crobe 0.5/^  in  diameter,  usually  arranged  in  pairs, 
sometimes  in  tetrads;  it  is  decolorized  by  the  Gram 
stain.  It  is  found  in  the  blood  adhering  to  the  red 
blood  corpuscles  or  situated  in  their  interior,  but  more 
especially  in  the  serosity  of  the  hemorrhagic  oedemas 
and  in  the  vessels  of  the  kidney.  It  also  exists  in 
the  vessels  of  the  intestinal  ulcers.  The  invaded  red 
blood  corpuscles  are  more  or  less  altered. 

The  rabbit,  by  inoculation  of  the  blood  or  oedema- 
tous  liquid,  as  well  as  by  ingestion  of  the  products 
of  the  disease  or  its  cultures,  contracts  a  general  dis- 
ease which  often  terminates  fatally.  In  the  ox,  the 
introduction  into  the  veins  or  connective  tissue  of  a 
considerable  quantity  of  blood  or  of  juice  expressed 
from  the  kidneys,  reproduces  the  typical  disease  with 
hsemoglobinuria.* 

*  [In  many  respects  similar  to  this  hsemoglobinuria  of  cattle  and 
to  a  closely  allied  disease  of  sheep  ("  Carceag  ")  also  investigated 


334  Manual  of  Veterinary  3Iicrobiotogy. 

Distemper  of  young  dogs. 

The  contaoiousness  of  this  disease  is  well  estab- 
lished  although  our  knowledge  of  the  germs  which 

by  Bab^s  is  the  disease  of  cattle  known  in  America  as  "Texas 
fever."  It  occurs  in  an  acute  and  in  a  mild  form,  the  latter  be- 
ing in  a  sense  endemic  in  the  southern  United  States,  whilst  the 
acute  form  prevails  in  northern  cattle  which  have  been  imported 
to  these  regions  or  which  have  been  exposed  to  the  infection 
brought  north  by  cattle  from  the  infected  districts.  The  chronic 
or  mild  type,  as  it  occurs  in  southern  cattle,  generally  passes  uu- 
perceived.  Mild  forms  of  the  disease  are  also  frequent  among 
northern  cattle,  especially  when  they  receive  the  infection  during 
the  cooler  weather  of  autumn.  The  acute  disease  (which  occurs  in 
the  northern  States  only  during  the  hot  weather  of  summer)  is 
generally  fatal;  in  non-fatal  cases  it  is  sometimes  followed  by  a 
prolonged  period  of  unthrift  and  debility.  Calves  are  less  sus- 
ceptible than  adult  animals  and  after  one  or  more  attacks  acquire 
a  certain  degree  of  immunity;  to  this  cause  is  attributed  the  com- 
parative immunity  possessed  by  cattle  native  to  the  southern 
States.  It  appears,  however,  that  this  immunity  is  not  perma- 
nent and  may  be  lost  when  such  cattle  are  kept  for  several  sum- 
mers in  non-infected  regions.  The  most  noticeable  symptoms  of 
the  acute  disease  are  those  of  an  intense  continuous  fever  with 
the  passage,  in  most  cases,  of  red  or  dark-red  colored  urine  ;  un- 
steady gait  and  muscular  tremors  in  the  neck  and  limbs  occur 
toward  the  last  stage  ;  occasionally  symptoms  of  delirium  are  ob- 
served. 

Pathological  anatomy. — The  most  important  lesions  observed  at 
the  autopsy  are :  Injection  of  the  vessels  and  occasionally  patches 
of  extravasation  in  the  subcutaneous  connective  tissue ;  blood 
thin  and  watery  (Smith),  or  frequently  of  normal  appearance; 
lungs  normal  or  discolored  by  congestive  patches;  heart  muscle 
congested,  points  of  extravasation  on  the  pericardium  and  endo- 
cardium ;  spleen  enlarged,  its  capsule  streaked  and  mottled  by 
the  injected  vessels,  pulp  dark  red  and  diffluent ;  liver  generally 
much  enlarged  and  darkened  from  blood  congestion  or  light  yel- 
low in  color  from  extreme  engorgement  with  bile  ;  gall  blad- 
der full  of  thick,  dark,  grumous  bile ;  kidneys  generally  congested. 


Mlcrohic  Diseases  Individually  Considered.       335 

determine  it  is  as  yet  incomplete  ;  some  authors  have 
described  a  bacillus  ;  others,  a  bacillus  and  a  coccus ; 

often  showing  irregular  discolored  patches  beneath  the  capsule 
which  itself  is  non-adherent,  points  of  extravasation  in  the  pelvic 
mucous  membrane ;  in  many  cases  extensive  effusion  of  bloody 
serosity  in  the  fat  and  connective  tissue  surrounding  one  or  both 
kidneys ;  the  urine  contained  in  the  bladder  generally  dark  red 
in  color  free  from  blood  corpuscles  but  strongly  albuminous, 
sometimes  of  normal  appearance ;  congestion  of  the  mucous  folds 
of  the  fourth  stomach ;  more  or  less  hyper£emia  and  extravasation 
in  the  walls  of  the  small  intestine  have  also  been  noticed. 

Etiology.— Te:s.as  fever  in  its  acute  and  best  known  form  occurs 
under  two  conditions,  1st,  when  northern  cattle  are  shipped  into 
southern  infected  regions,  and  second,  when  cattle  from  perma- 
nently infected  regions,  brought  north  during  the  summer  months, 
infect  pastures  in  which  susceptible  cattle  are  subsequently  al- 
lowed to  graze.     In  the  first  case  the  disease  may,  and  frequently 
does,  appear  two  weeks  after  exposure  to  infection,  in  the  second 
a  lapse  of  six  weeks  or  more  intervenes  between  the  arrival  of  the 
infection-bearing  cattle  and  the  outbreak  of  the  disease.     These 
differences  are  attributable  to  the  method  by   which  the  infec- 
tion is  conveyed  into  the  bodies  of  susceptible  animals.     The  in- 
vestigations of  Smith  and  Kilborne  (afterward  repeated  with  the 
same  results  by  others)  have  shown  that  this  takes  place  through 
the   intermediation  of  cattie  ticks  {Boophilus  bovis,  Curtice),  the 
progeny  of  those  adherent  to  the  skin  of  the  southern  cattle. 
The  lapse  of  time  between  the  arrival  of  these  cattle  and  the  out- 
break of  the  disease  represents  the  time  required  for  the  incuba- 
tion of  the  next  generation  of  these  parasites  along  with  the  pe- 
riod of  incubation  of  the  disease.    In  the  case  of  cattle  shipped 
into  permanently  infected  districts  their  invasion  by  ticks  and 
consequent  infection  may  begin  at  once.     It  is  possible  also  that  in 
permanently  infected  districts  infection  may  occur  by  other  means. 
Later  generations  of  ticks  which  come  to  development  on  sus- 
ceptible cattle  in  the  North  are  also  capable  of  communicating 
the  disease.     Horses,  which  may  also  be  invaded  by  these  para- 
sites, do  not  obtain  the  disease,  and  the  progeny  of  ticks  which 
have  developed  on  these  animals  have  not  been  shown  to  be  dan- 
gerous for  cattle. 

Experimental  inoculations.— TositWe  results  have  been  obtained 


836 


Manual  of  Veterinary  31icrobiology. 


and  others,  again,  attribute  the  disease  to  a  micro- 
coccus.    We  have  found  as  the  result  of   our   own 

by  Smith  by  intra-venous  and  subcutaneous  injection  of  suscep- 
tible cattle  with  the  blood  of  animals  suffering  from  the  disease 
as  well  as  with  the  blood  of  apj)arently  healthy  southern  cattle. 
No  other  animal  species  has  been  found  to  be  susceptible.  Direct 
contagion  seems,  however,  rarely  or  never  to  occur  under  natural 
conditions. 

Microbe.— Cover  glass  preparations  from  the  blood,  spleen,  liver, 
kidney,  and  heart  muscle  of  cattle  which  have  died  from  acute 
Texas  fever,  show  the  presence  of  a  rounded  or  somewhat  ovoid, 
or  pyriform  (Smith)  body,  isolated,  in  pairs,  or  occasionally  three 
or  four,  within  a  certain  proportion  of  the  red  blood  corpuscles. 
They  are  usually  extremely  abundant  in  the  juice  of  the  kidney 
(where  they  also  occur  between  the  cellular  elements),  less  so  in 
the  liver  and  spleen,  and  still  less  in  blood  from  the  large  ves- 
sels or  heart.  These  stain  readily  with  aqueous  solutions  of  ani- 
line colors  (methylene  blue),  as  well  as  with  hsematoxylin  (Dela- 
field's).    Their  outline  after  staining  is  generally  less  well  defined 

than  bacteria 
similarly  stain- 
ed ;  neverthe- 
less their  ap- 
pearance with- 
in the  unstain- 
ed disk  of  the 
red  blood  cells  is 
quite  character- 
istic and  in  the 
absence  of  other 
evidence  is  of 
itself  sufficient 
for  a  diagnosis 
of  the  disease. 

Culture  tests  of 
the  blood  and 
organs  in  cases 
of  Texas  fever 
have,  in  gener- 
Billings  obtained  an  ovoid  "  bi-polar  " 


oo 


Smear  preparation  from  kidney  of  ox. 
Texas  Fever.     XIOOO.     (D.) 

al,  led  to  negative  results. 


Acute 


3Iicrohic  Diseases  Individually  Considered.      337 

researches,  bearing  upon  four  subjects  only,  that 
a  micrococcus  in  pure  culture  is  always  present 
in  the  pustules  of  the  cutaneous  form.  M.  Mathis 
has  recorded  in  a  special  work  the  results  of  his  in- 
vestigations, lie  succeeded  in  demonstrating  in  the 
contents  of  pustules,  in  the  discharge  from  the  nos- 
trils, in  the  blood  and  in  the  tissues,  the  presence  of 
spherical  micrococci,  isolated  or  grouped  in  pairs, 
in  chains,  or  in  masses  ;  these  measure  0-1//  to  0-3//  in 
diameter.  He  cultivated  these  organisms  in  bouil- 
lon;  this  medium  becomes  turbid,  then,  after  fifteen 
to  twenty  days,  clears  again  by  the  deposition  of  the 
suspended  germs  at  the  bottom  of  the  vessel. 

Subcutaneous  inoculation  of  these  cultures  in  sus- 
ceptible dogs  is  followed  by  an  cedematous  tumefac- 
tion, with  pustules  on  the  skin  in  the  region  of  the 
inoculation  ;  generally  there  is  an  elevation  of  tem- 
perature and  occasionally  generalization  of  the  pus- 
tulous eruption,  with  cough,  discharge  from  the  nose, 
etc.,  and  if  young  subjects  are  experimented  with, 
the  disease  may  terminate  fatally. 

staining  bacterium,  pathogenic  for  small  animals,  which  he  de- 
scribes as  the  cause  of  the  disease.  Smith,  to  whose  investiga- 
tions our  knowledge  of  the  etiology  of  Texas  fever  is  chiefly  due, 
regards  the  intra-corpuscular  body  already  mentioned,  which  he 
discovered  in  1889,  as  the  causative  agent  of  this  disease.  He  de- 
scribes it  as  occurring  in  several  forms  representing  different 
stages  in  its  development ;  the  parasite,  according  to  this  author, 
belongs  to  the  protozoa  (Pyrosoma  bigeminum).  The  destruction 
of  red  blood  corpuscles,  the  essential  characteristic  of  this  disease, 
is  brought  about  by  the  direct  action  of  the  parasite.  The  latter 
exhibits  amoeboid  motion  within  the  corpuscle  which  it  ultimately 
destroys  and  then  is  found  in  its  fi'ee  stage  between  the  cellular 
elements.     Attempts  at  cultivation  were  unsuccessful. — D.] 

29 


338  Manual  of  Veterinary  Microbiolof/y. 

The  experimental  disease  confers  immunity.  M. 
Mathis  has  found  that  immunity  also  follows  the 
natural  disease. 

^"otwithstanding  the  importance  of  the  results  al- 
ready obtained  concerning  the. etiology  of  distemper 
of  dogs,  there  are  some  obscure  points  which  yet  re- 
quire to  be  elucidated,  such  as,  for  instance,  the  inter- 
esting question  of  the  pathogenesis  of  those  nervous 
troubles  which  so  frequently  complicate  the  disease. 

Phosphorescent  meats. 

Dead  animal  matters  not  unfrequently  become 
phosphorescent.  Marine  iishes  and  moUusks  are 
especially  liable  to  be  thus  aftected,  while  meats  are 
less  subject  to  this  change.  Phosphorescent  meat 
shows  on  its  surface  a  coating  which  is  luminous  in 
the  dark,  and  easily  removed  by  scraping. 

The  cause  of  this  deterioration  resides  in  a  bacte- 
rium, Ifjt  in  length  {Photohacteriam  Pflugerii).  This 
germ  grows  well  on  meat  and  fish,  especially  at  tem- 
peratures between  10°  and  30°.  In  presence  of  oxy- 
gen it  gives  to  the  culture  media  a  whitish  glimmer. 
The  invasion  of  meat  takes  place  very  quickly  in 
summer,  one  piece  of  meat  being  readily  infected  by 
another.  The  multiplication  of  the  germ  is  rather 
favored  by  salting,  and  it  ceases  when  putrefaction 
begins.  The  luminous  property  is  directly  connected 
with  the  life  of  the  germ.  It  has  not  hitherto  been 
found  that  such  meats  are  poisonous. 

In  order  to  complete  this  subject  we  should  yet 
have  to  discuss  a  number  of  diseases  the  microbic 
nature  of  which  is   unquestionable.     Thus,  cocci  and 


Microhic  Diseases  Individually  Considered.      389 

streptococci  have  been  described  in  the  vesicles  of 
aphthous  fever,  bacilli  in  rinderpest,  micrococci  in 
cow-pox  or  vaccinia,  as  well  as  in  enzootic  hepatitis 
of  young  pigs,  etc.  But  not  only  is  there  a  lack  of 
unanimity  as  to  the  morphology  of  the  germs  of 
these  diseases,  but  the  study  of  their  special  biologi- 
cal characters  has  yet  entirely  to  be  made,  hence,  a 
particular  acquaintance  with  these  germs  is  only  of 
secondary  importance  to  the  practitioner. 


340 


Appendix. 


APPENDIX. 

(From  Attfield's  Chemistry.) 

The  Metric  System  of  weights  and  measures  is 
founded  on  the  meter.  The  engraving  represents  a 
pocket  folding  measure,  the  tenth  part  of  a  meter  in 
length,  divided  into  ten  centimeters,  and  each  centi- 
meter into  ten  millimeters : 

Fig.  19. 


HEmr 

iiii|iiii 

UKUR 

JULm 

mmnffliiniinrnn 

l!ll  Nil 

INI  INI 

1 1 11  II II 

1 

2 

3 

4 

fM\     »       ' 

a 

1 

« 

[O) 

The  Decimeter. 


The  units  of  the  system  with   their  multiples  and 
Bubmultiples  are  as  follows  : 


UNITS. 

Length. — The  Unit  of  Length  is  the  meter,  derived 
from  the  measurement  of  the  quadrant  of  a  meridian 
of  the  earth.  (Practically,  it  is  the  length  of  certain 
carefully-preserved  bars  of  metal  from  w^hich  copies 
have  been  taken.) 

Surface. — The  Unity  of  Surface  is  the  are,  which  is 
the  square  of  ten  meters. 

Capacity. — The  Unity  of  Capacity  is  the  liter, 
which  is  the  cube  of  a  tenth  part  of  a  meter. 

Weight.— The  Unit  of  Weight  is  the  gramme,  which 
is  the  weight  of  that  quantity  of  distilled  water,  at 


Appendix. 


341 


its  maximum  density  (4  C),  which  fills  a  cube  of  the 
one-hundredth  part  of  the  meter. 


TABLE. 


Note. — Multiples  are  denoted  by  the  Greek  words  "  Deca,"  Ten, 
"  Hecto,"  Hundred,  "  Kilo,"  Thousand. 

Subdivisions,  by  the  Latin  words,  "  Deci,"  One-tenth,  "  Centi," 
One-hundredth,  "  Milli,"  One-thousandth. 


■  Quantities. 

Length 

Surface. 

Capacity. 

Weight. 

1000 

100 

10 

1  (Units) 
.1 
01 
001 

Kilo-raeter 

Hecto-meter 

Deca-meter 

Meter 

Deci-meter 

Centi-meter 

Milli-meter 

Hectare 

Are 

Centiare 

Kilo-liter 

Hecto-liter 

Deca-liter 

Liter 

Deci-liter 

Centi-liter 

Milli-liter 

Kilo-gramme 

Hecto-gramme 

Deca-Gramme 

Gramme 

Deci-gramme 

Centi-gramme 

Milli-gramme 

Relation  of  Metric  to  United  States  measures  of 
Length,  Capacity,  and  Weight : 


1  Meter,     . 
1  Decimeter, 
1  Centimeter, 
1  Millimeter, 


39.370432  inches. 
3.937043      " 
0.393704      " 
0.039370      " 


Approximately,  1  centimeter  (cm.)  =  |  in.;  1  millimeter  (mm.) 
=  ^V  in.;  or  conversely,  1  in.  =  2\  cm.  =  25  mm. 
In  micrometry,  1   Micron  (//)  =  0.001  mm.  =  0.00004  in.  = 

(Milliliter)  ]  cubic  centimeter  (com.)  : 
(Liter)         1,000  cubic  centimeters  = 

Approximately,  1  liter  =  1  quart. 


16.23  minims. 
33.81  fluidounces. 


1  Gramme  (weight  of  1  ccm.  of  water  at  4°  C.)  =  15.432  grains. 
1  Kilogramme  (1,000  grammes)  =  15432.350  grains. 

Approximately,  1  kilogramme  =  2  lbs.,  Avoir. 


342 


Appendix. 


Thermometric  scales. — On  the  Centigrade  (C.)  scale 
the  freezing  point  of  water  is  made  zero,  and  the 
boiling  point  100  ;  on  the  Fahrenheit  (F.)  scale  the 
zero  is  placed  32  degrees  below  the  congealing  point 
of  water,  the  boiling  point  of  which  becomes,  conee- 
quently,  212. 

The  degrees  of  one  scale  are  easily  converted  into  those 
of  another  if  their  relations  be  remembered — namely  : 
180  (F.),  100  (C.) :  that  is,  18  to  10,  or  o'to  5. 

Formul<B  for  the  Conoersion  of  Degrees  of  one  Ther- 
mometric Scale  into  those  of  another : 

F  =  Fahrenheit;  C  =  Centigrade  ;  D  =  The  observed  degree. 

If  above  the  freezing  point  of  water  (32°  F.;  0°  C), 

F  into  C,  .  .  .         (D  —  32)  --  9  X  5. 

C  into  F,       .  .  .  D  H-  5  X  9  +  32. 

If  below  freezing,  but  above  0°  F  (—  17°-77  C), 

F  into  C,  .  .        —  (32  —  D)  -H-  9  X  5. 

C  into  F,       .        .  .  32  —  (D  ^  5  X  9. 

If  below  0°  F  (—  17°  '77  C), 

FintoC,  .  .  .        —  (D  +  32)-^9X5. 

CintoF,       .  .  .  —  (D-r-5X9)  — 32. 

Equivalents  on  the  Centegrade  and  Fahrenheit 
scales  : 


c 

F 

C 

F 

C 

F 

C 

F 

C 

F 

—10 

14 

25 

77 

37 

9S  60 

44 

111  20 

75 

167 

0 

32 

28 

82  40 

38 

100  40 

45 

113 

80 

176 

+5 

41 

30 

86 

39 

102  20  i 

50 

122 

90 

194 

10 

50 

32 

89  60 

40 

104   ! 

^ri 

131 

100 

212 

15 

59 

34 

93  20 

41 

105  80  i 

60 

140 

120 

248 

20 

68 

35 

95 

42 

107  60 

65 

149 

150 

302 

22 

71  60 

36 

96  80 

43 

109  40 

70 

158 

200 

392 

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